OBD-II Code P1021: A Manufacturer-Specific Fault Guide

What Does P1021 Mean?

P1021 indicates an electrical or performance fault in a critical engine component. As a manufacturer-specific code, its definition varies entirely by make: Nissan points to the electronic turbo actuator, Honda and Mitsubishi flag the variable valve timing (VVT) oil control solenoid, and Porsche signals a high-pressure fuel pump (HPFP) failure.

Technical definition: As a P1xxx code, P1021 is manufacturer-specific. For Nissan, it is 'Turbocharger (TC) Boost Control Actuator - Incorrect Signal.' For Honda/Mitsubishi, it is 'Engine Oil Control Valve Circuit Malfunction.' For Porsche, it is 'Fuel High Pressure Quantity.' For VAG, it indicates a 'Throttle Valve Error.'

Can I Drive With P1021?

⚠️Yes, But With Caution. You can drive, but the vehicle enters 'limp mode' with significantly reduced power. Drive only to the nearest repair shop. On turbo models, continuing to drive causes excessive exhaust temperatures, damaging the turbocharger or DPF and adding $1,500-$4,000 to repair costs.

Common Causes

• Faulty Electronic Turbo Actuator (Nissan) (Very Common) — The internal electric motor or plastic gears inside the actuator wear out, preventing it from controlling the turbo vanes. This is the primary cause of P1021 in affected Nissan models.
• Contaminated or Low Engine Oil (Honda/Mitsubishi) (Very Common) — Sludge from old oil or low oil levels clogs the filter screens in the variable valve timing (VTEC/MIVEC) oil control valve, preventing the solenoid from functioning.
• Failed High-Pressure Fuel Pump (Porsche) (Common) — The high-pressure fuel pump wears internally and fails to deliver the 40-120 bar of pressure requested by the ECU, triggering the fault.
• Poor Electrical Connection or Damaged Wiring (Common) — The electrical connector to the actuator or solenoid becomes loose, corroded, or contaminated with oil, interrupting the signal. Cleaning and re-securing the connector often resolves the issue.
• Sticking or Seized Turbocharger Vanes (Common) — Soot and carbon buildup from the exhaust cause the variable geometry vanes inside the turbocharger to stick. This forces the actuator motor to overwork and burn out.
• Internal Short in Throttle Body (VAG) (Less Common) — Oil vapor and carbon from the EGR system seep into the throttle body's electronics or cause the butterfly valve to stick, triggering a throttle valve error.
• Blown Fuse or Faulty Relay (Rare) — A blown fuse or a faulty engine control relay cuts power to the VVT oil control solenoid, instantly triggering the circuit malfunction code.

Symptoms

• Vehicle Enters 'Limp Mode' with Drastic Power Loss — The ECU intentionally limits engine power and caps RPM (often at 3,000 RPM) to prevent damage. The vehicle feels sluggish and struggles to accelerate.
• Check Engine Light On — The Malfunction Indicator Lamp (MIL) illuminates immediately upon the ECU detecting the fault.
• Intermittent Performance — The power loss occurs randomly and resolves after restarting the engine, only to return later as the electronic fault reappears.
• Audible Clicking or Grinding Noises — A failing turbo actuator produces a grinding sound upon startup as it attempts to cycle. A faulty VVT solenoid emits a rapid clicking noise.
• Poor Fuel Economy (also visible on scanner) — Inefficient engine operation due to a disabled turbo, locked VVT system, or failing fuel pump causes a 10-25% drop in fuel mileage.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Clean and Re-secure Electrical Connector — Parts: $5-$15, Labor: $0-$50, ~0.2 hr book time (DIY)
• Replace VVT/MIVEC Oil Control Solenoid (Honda/Mitsubishi) — Parts: $50-$150, Labor: $75-$150, ~0.8 hr book time (DIY)
• Replace Electronic Turbo Actuator (Nissan) — Parts: $150-$350, Labor: $150-$250, ~1.5 hr book time (Intermediate)
• Replace High-Pressure Fuel Pump (Porsche) — Parts: $1000-$1500, Labor: $300-$500, ~3.5 hr book time (Professional)
• Clean Turbocharger Vanes (if seized) — Parts: $20-$40, Labor: $400-$800, ~5.0 hr book time (Professional)
• Replace Entire Turbocharger Assembly — Parts: $1000-$2500, Labor: $600-$1200, ~8.5 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: For high-cost, low-wear mechanical assemblies like a complete turbocharger from a low-mileage donor vehicle. Avoid used electronic components like actuators or VVT solenoids.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Verify the part number exactly, as many components look identical but are not interchangeable.
• Avoid cheap, unbranded aftermarket electronics, which have poor build quality and fail quickly.
• Prefer OEM-supplier brands (e.g., Bosch/Hitachi for fuel pumps, Hella for actuators) over generic parts.

Decision logic:

• If The part is a high-wear electronic component like a VVT solenoid or turbo actuator → Buy new from an OEM or reputable OEM-supplier brand. The risk of premature failure on a used part is too high.
• If The part is a high-cost mechanical assembly like a Porsche HPFP or a complete turbo → A used or remanufactured unit from a reputable source is a viable option to save money.
• If The vehicle is over 150,000 miles and budget is the primary concern → A used part is acceptable, but understand it carries a higher risk of failure.

Warranty tradeoff: Used parts from salvage yards typically offer a 30-90 day warranty. Aftermarket new parts offer 1-year to limited lifetime warranties. New OEM parts carry the manufacturer's standard warranty.

Worst-case if a used part fails: $500-$1500 if a used part fails after the warranty period, requiring you to pay for labor and a replacement part a second time.

What Happens If You Wait — Timeline

1. 0-1 month: Intermittent limp mode, usually reset by restarting the engine. Noticeable hesitation occurs, but the vehicle remains drivable. (MPG impact: 5-10%% · Added cost: $0-$100 in wasted fuel.)
2. 1-3 months: Limp mode becomes constant. Turbo models experience consistently low boost. VVT models suffer rough idle and stalling at low speeds. (MPG impact: 10-20%% · Added cost: $100-$300. Increased strain on the engine and exhaust system begins.)
3. 3-6 months: Excessive soot from poor combustion clogs the Diesel Particulate Filter (DPF) or catalytic converter. Porsche HPFP weakness causes hard starts. (MPG impact: 20-35%% · Added cost: $1,500-$4,000 for a new DPF or catalytic converter.)
4. 6+ months: Cascading failures occur. A completely clogged DPF damages the turbo seals. Driving with a bad VVT solenoid stretches the timing chain. (MPG impact: 35-50%% · Added cost: $2,000-$7,000+ for combined engine and exhaust repairs.)

Cost of Not Fixing It

• 0-1 month: Persistent limp mode, significantly reduced power, and a 10-25% drop in fuel economy. Increased stress on other components due to inefficient engine operation. (Added cost: Negligible, but fuel costs increase.)
• 1-6 months: A stuck-closed turbo actuator causes overboost and head gasket failure. A stuck-open actuator causes excessive soot, clogging the DPF or catalytic converter. (Added cost: $1500-$4000)
• 6+ months: Ignoring a VVT solenoid issue accelerates timing chain wear. A failing Porsche HPFP eventually causes a no-start condition and damages the in-tank lift pump. (Added cost: $2000-$5000+)

Diagnosis Steps

1. Read Fault Codes
   Use an OBD-II scanner to confirm P1021 is active. Note any accompanying codes (e.g., P0299, P1025), as they provide critical diagnostic clues. Verify the exact code definition for your specific vehicle make.
   Tools: OBD-II Scanner (Beginner)
2. Inspect the Component and Wiring
   Locate the relevant component (turbo actuator, VVT solenoid, HPFP). Visually inspect the wiring harness for fraying, melting, or oil contamination. Ensure the electrical connector is securely plugged in.
   Tools: Flashlight (Beginner)
3. Clean the Electrical Connector
   Disconnect the component's electrical plug. Spray both the plug and socket with electrical contact cleaner and use a small brush to remove corrosion. Reconnect firmly, clear the codes, and test drive.
   Tools: Electrical Contact Cleaner, Small Brush (Beginner)
4. Check Engine Oil Level and Condition (Honda/Mitsubishi)
   Pull the dipstick and check the oil. If the oil is below the minimum line or appears thick and sludgy, it is starving the VVT solenoid. Perform an oil change before replacing any parts.
   Tools: Dipstick, Clean Rag (Beginner)
5. Observe Actuator/Solenoid Operation
   For a turbo actuator, have a helper turn the ignition on (without starting). The actuator arm must cycle smoothly. If it doesn't move or grinds, it has failed. For a VVT solenoid, listen for a 'click' when commanded on.
   Tools: Helper (Intermediate)
6. Check for Mechanical Binding (Turbo Only)
   With the engine off and cool, disconnect the clip holding the actuator rod to the turbo's lever. Move the lever by hand. It must move smoothly; if it is stiff, the turbo's internal vanes are seized with carbon.
   Tools: Pliers, Screwdriver (Advanced)
7. Test with a Bi-Directional Scan Tool
   Command the actuator or solenoid to operate using a professional scan tool. Command the turbo actuator from 0-100% and watch the rod move, or toggle the VVT solenoid to verify its function.
   Tools: Bi-Directional Scan Tool (Advanced)
8. Analyze Live Data (Porsche HPFP)
   Monitor live data for 'Fuel High Pressure Set Point' and 'Actual Value'. At idle, both should read ~40 bar (~580 PSI). If the actual value is stuck around 5.5 bar (~80 PSI), the high-pressure pump has failed.
   Tools: Advanced OBD-II Scanner (Advanced)
9. Measure Actuator/Solenoid Resistance
   Disconnect the component and measure the resistance across its terminals. Compare this to the manufacturer's specification (e.g., 6.9-7.9 Ω for a Mitsubishi MIVEC solenoid). An open or shorted reading confirms a dead component.
   Tools: Multimeter, Service Manual (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Engine Coolant Temp: 180-205°F (82-96°C) (The fault occurs once the engine is fully warmed up and operating in closed-loop mode.)
• Engine RPM: 1500-2500 RPM (The code sets during steady-state cruising or light acceleration, rather than high-load situations.)
• Engine Load: 30-60% (The engine is under moderate load, such as climbing a slight incline, where the ECU expects a specific response from the turbo or VVT system.)
• Vehicle Speed: 35-60 mph (56-97 km/h) (Logged during standard city or highway driving, consistent with moderate RPM and load conditions.)

Related Codes

• P1020 — Indicates 'Turbocharger Boost Control Actuator - Performance' and often appears alongside P1021.
• P0299 — A generic code for 'Turbocharger Underboost Condition.'
• P1025 — On Porsche vehicles, this 'Fuel Pressure Implausible' code frequently accompanies P1021.
• P0121 — On VAG vehicles, a P1021 'Throttle Valve Error' is often accompanied by this throttle position sensor code.

Climate & Environmental Factors

• Cold Weather: Extreme cold thickens engine oil, straining VVT solenoids and causing them to respond slowly. It also freezes condensation inside turbo actuators, causing mechanical binding.
• High Humidity / Water Ingress: Moisture causes condensation inside electronic components. Poorly sealed connectors allow water ingress, corroding the internal circuit board and triggering the electrical fault.
• Extreme Heat: Sustained high temperatures degrade the electronic components within a turbo actuator. Excessive heat also breaks down engine oil, accelerating the sludge buildup that clogs VVT solenoids.

How to Talk to a Mechanic About This Code

Say this: "I have a P1021 code on my [Make]. For my Porsche, please check live data for fuel pressure setpoint vs. actual before recommending a new HPFP. For my Nissan, please confirm if the turbo actuator cycles on startup and if the turbo vanes are mechanically free before quoting a full turbo replacement."

This language directs the mechanic toward a specific, logical diagnostic path, preventing them from jumping to the most expensive conclusion and protecting you from common upsells.

Avoid saying:

• 'My check engine light is on.' (Too vague, invites a wide-ranging and expensive diagnostic process).
• 'Just fix whatever is wrong.' (Gives the shop a blank check to replace parts without your approval).
• 'My truck is in limp mode, I think the turbo is blown.' (Don't diagnose it for them; describe the symptoms and provide the code).

Questions to ask before authorizing the repair:

• (Porsche) Can you show me the live data graph of the requested vs. actual fuel pressure?
• (Nissan) Did you confirm the actuator is bad, or are the turbo vanes seized? What was the result of the manual check?
• (Honda) Was the oil level and condition checked before recommending a new VVT solenoid?
• Is this part from the OEM, an OEM supplier, or a standard aftermarket brand?
• What is the warranty on both the parts and the labor for this repair?

Where to Take It: Dealer vs Independent vs Chain

• Dealer: Recommended for Porsche due to tool requirements. Use for Nissan/Honda only if under warranty.
  Best for: Porsche HPFP diagnosis requiring the proprietary PIWIS scan tool., Vehicles still under a powertrain or extended warranty., Complex electrical issues on newer German vehicles.
  Downsides: Highest labor rates., May only offer a complete turbo assembly replacement for a Nissan, even if only the actuator is bad. (Typical cost: +50% vs. baseline)
• Independent Shop: Best overall fit for Nissan and Honda/Mitsubishi repairs. A good European specialist is a viable alternative to the dealer for Porsche.
  Best for: Nissan turbo actuator and Honda VVT solenoid replacements on out-of-warranty vehicles., Shops specializing in Japanese or European vehicles., Cost-effective diagnosis and repair.
  Downsides: Quality and expertise vary greatly; vet shops carefully., May lack the expensive, specialized tools for a deep Porsche diagnosis. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID for diagnosis and repair of P1021. The nuanced, make-specific nature of this code is a poor fit for their business model.
  Best for: Reading the initial code for free., Simple related maintenance like an oil change for a Honda VVT issue.
  Downsides: Technicians lack the specialized experience for make-specific codes like P1021., High risk of misdiagnosis and upselling. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost exceeds 40-50% of the car's private-party value, sell or trade in the vehicle instead of repairing it.

• Car worth $6000, fix is $1950: Walk away. The HPFP repair cost on this older Porsche Cayenne is a significant portion of its value.
• Car worth $12000, fix is $650: Fix it. Replacing the turbo actuator on a Nissan Navara is well below the threshold and a common repair.
• Car worth $2500, fix is $1500: Walk away. The repair cost is over 50% of the vehicle's value.

What Scan Tool You Need for This Code

Minimum: A scanner that reads manufacturer-specific codes and views live data streams. A generic $20 reader cannot differentiate a Nissan P1021 from a Porsche P1021.

To diagnose P1021, you must see what the ECU sees. For a Porsche, this means graphing 'Actual' vs. 'Setpoint' fuel pressure. Without live data, you are guessing.

Budget: Foxwell NT301 / BlueDriver Pro (~$70-120) — Confirms the manufacturer-specific P1021 code and displays live data. BlueDriver graphs fuel pressure or sensor voltage on a smartphone, sufficient for confirming a bad HPFP or VVT solenoid.

Mid-range: Autel MaxiCheck MX808S / Launch CRP129X (~$250-400) — Adds bi-directional control. This allows you to command the Nissan turbo actuator to cycle or the Honda VVT solenoid to click, directly testing the component from the tool.

Professional: Autel MaxiCOM MK906BT / Launch X431 Series (~$600-1200) — Provides full, dealer-level diagnostic functions, including coding and adaptations necessary after replacing certain components on European vehicles.

Rent vs buy: Auto parts stores read codes for free using basic readers. To properly diagnose P1021, you need live data, making a budget-pick purchase a smart investment to avoid shop misdiagnosis.

How to Clear the Code After You Fix It

1. Use an OBD-II scan tool to clear the code
2. Perform a complete drive cycle to reset readiness monitors
3. Check for pending or permanent codes after the drive cycle

Drive cycle (~30 minutes): A general drive cycle includes a cold start (engine off for 8+ hours), a 2-3 minute idle, 10-15 minutes of steady highway driving (55-60 mph), a coast-down without braking to 20 mph, and 5-10 minutes of stop-and-go city driving. Do not use cruise control.

Readiness monitors affected: Catalyst Monitor, Oxygen (O2) Sensor Monitor, EVAP System Monitor

Before emissions retest: drive at least 50 miles to fully set monitors.

Watch out for:

• Clearing the code with a scanner resets the fault but does not reset the readiness monitors; a drive cycle is mandatory.
• The code returns immediately if the root cause of the fault was not correctly repaired.
• Not having the fuel tank between 1/4 and 3/4 full prevents the EVAP monitor from running.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: An active P1021 code causes an automatic failure. After repair, a full drive cycle must be completed to set all readiness monitors before a re-test.
• New York: A vehicle with an illuminated Check Engine Light for P1021 automatically fails the OBD-II portion of the NYS inspection.
• Texas: In the 17 counties requiring emissions testing, an active P1021 code results in an automatic failure.

Most Commonly Affected Vehicles

• Nissan Navara (D40) (2005-2015) — Extremely common on the 2.5L YD25DDTi diesel engine. The electronic actuator is a known failure point.
• Nissan Pathfinder (R51) (2005-2012) — Shares the YD25DDTi engine and turbocharger setup with the Navara, making it equally susceptible to actuator failure.
• Nissan Titan XD (2016-2019) — Affects the 5.0L Cummins Diesel engine, where the electronic wastegate actuator fails.
• Porsche Cayenne (2008-2018) — On V8 models, P1021 points to the high-pressure fuel pump failing to achieve target pressure.
• Honda Civic, Accord, CR-V, Fit (2003-2024) — Indicates a fault in the VTC oil control valve caused by low/dirty oil or a failed solenoid.
• Mitsubishi Lancer, Eclipse, Outlander (2004-2012) — Refers to the MIVEC variable valve timing 'Engine Oil Control Valve Circuit'.
• Skoda / Volkswagen Superb, Passat, Golf (TDI) (2008-2015) — Points to a 'Throttle Valve Error' caused by heavy carbon buildup from the EGR system.
• Infiniti QX70 / FX Series (2009-2017) — Diesel variants sold outside North America use powertrains susceptible to this turbo actuator fault.

Manufacturer-Specific Notes

• Nissan / Infiniti: The most common user of P1021, where it exclusively refers to the electronic turbocharger actuator failing.
• Porsche: P1021 relates to 'High Pressure Fuel Pump Pressure.' Porsche offers a 'Vehicle Service Protection' extended warranty that covers these pumps for up to 10 years or 100,000 miles.
• Honda / Acura: P1021 is defined as 'Valve Pause System Stuck On' or an issue with the VTC oil control valve circuit.
• Mitsubishi: P1021 refers to the 'Engine Oil Control Valve Circuit' within the MIVEC variable valve timing system.
• VAG (Volkswagen, Audi, Skoda): P1021 points to a 'Throttle Valve Error,' almost always caused by carbon buildup or oil contamination inside the throttle body.
• BMW: P1021 relates to the Valvetronic system ('Valvetronic Adjustment Range') and has nothing to do with the turbocharger.
• Toyota: Generic scanners frequently misinterpret Toyota code P1121 as P1021. On a Prius, P1121 points to a faulty Coolant Flow Control Valve (TSB EG001-08).

Real Owner Stories

2011 Nissan Navara D40 with intermittent power loss

The truck randomly lost power and entered limp mode, resolving only after a restart. The code was P1021.

What they tried:

1. Took it to a mechanic who could not replicate the intermittent issue.
2. Inspected the electrical connector to the turbo actuator based on forum advice.

Outcome: The owner found a loose, dirty electrical connection at the turbo actuator. Cleaning and re-securing the connector restored full power permanently.

Lesson: For intermittent electronic faults, always inspect and clean the component's electrical connector before buying expensive replacement parts.

2011 Porsche Cayenne S (V8) stalling when braking

The car stalled when coming to a stop and logged a P1021 code. The owner assumed the high-pressure fuel pump (HPFP) was dead.

What they tried:

1. Replaced the HPFP with a new OEM unit, but the problem persisted.
2. Replaced the low-pressure fuel pump, spark plugs, and coils.
3. Finally used a scan tool to monitor live fuel pressure data, noticing pressure drops only after long drives.

Outcome: The misdiagnosis cost over $1,500. The actual issue was a failing fuel pressure sensor, not the pump itself.

Lesson: Never replace a Porsche HPFP based solely on a fault code. Always use a scan tool to analyze live requested vs. actual fuel pressure data first.

Honda CR-V with rough idle and P1021

The owner experienced a rough idle, poor fuel economy, and a P1021 code pointing to the VVT system.

What they tried:

1. Ignored the issue until the engine began hesitating on acceleration.
2. Performed an oil change and replaced the VVT solenoid.

Outcome: Replacing the solenoid and changing the sludgy oil resolved the rough idle and cleared the code for under $100.

Lesson: On Honda/Acura vehicles, P1021 is almost always caused by engine oil sludge or low oil levels starving the VVT solenoid. Always check your oil first.

How to Prevent This Code From Triggering

• Perform regular oil changes with high-quality synthetic oil (Every 5,000-7,500 miles) — Clean oil prevents the formation of sludge that clogs the tiny passages and filter screens in VVT/MIVEC oil control solenoids.
• Allow a brief cool-down period after hard driving (After towing or spirited driving) — Idling for 60 seconds before shutdown prevents heat soak, protecting the turbo actuator's electronics and preventing oil coking inside the turbocharger.
• Inspect and clean key electrical connectors (Annually or during oil changes) — Prevents water and oil ingress from corroding the turbo actuator or VVT solenoid connectors, stopping electrical faults before they trigger limp mode.
• Avoid frequent short trips (Daily habit) — Short trips prevent the engine from reaching optimal temperature, accelerating sludge formation in the oil and carbon buildup in the exhaust.

Frequently Asked Questions

Can I just replace the actuator, or do I need a whole new turbo?

If the actuator fails electronically but the turbo vanes move freely, you can replace just the actuator. However, many shops only sell the complete turbocharger assembly because seized vanes often cause the initial actuator failure. Always manually test the turbo lever before buying parts.

How long can I drive in limp mode?

Limp mode is designed strictly to get you to the nearest safe location or repair shop. Continuing to drive puts severe strain on the engine and exhaust system. On turbo models, this causes excessive exhaust temperatures that destroy the DPF or catalytic converter.

What are the most common misdiagnoses for P1021?

The most common mistake is replacing an expensive component like a turbo actuator or fuel pump without checking the electrical connector first. Another major error is ignoring the vehicle make, as a Nissan P1021 requires a completely different diagnostic path than a Porsche P1021. Always verify the code definition for your specific vehicle.

My scanner shows P1021 on my Toyota Prius, but it doesn't have a turbo. What's wrong?

Generic scanners frequently misinterpret Toyota code P1121 as P1021. On a Prius, P1121 points to a faulty Coolant Flow Control Valve, a known issue covered by Toyota TSB EG001-08. Replace the coolant valve to resolve the issue.

Could a dirty electrical plug really cause my truck to lose all its power?

Yes, a dirty electrical plug interrupts the precise voltage signals required by the turbo actuator or VVT solenoid. When the ECU loses this signal, it defaults to limp mode to protect the engine. Cleaning the connector with electrical contact cleaner often restores full power.

What happens if I don't fix a P1021 code?

Ignoring P1021 causes persistent limp mode, terrible fuel economy, and automatic emissions test failures. Over time, a bad turbo actuator destroys the turbocharger, while a faulty VVT solenoid accelerates timing chain wear. These cascading failures turn a $200 repair into a $3,000+ engine or exhaust replacement.

Is P1021 covered under any recalls?

Widespread recalls for P1021 are rare, though Nissan has documented factory defects with certain turbo actuators. Porsche offers a 'Vehicle Service Protection' extended warranty that covers high-pressure fuel pumps for up to 10 years or 100,000 miles. Always check your VIN with a dealership for open service campaigns.

Key Takeaways

• P1021 is a manufacturer-specific code that points to a failed electronic turbo actuator on Nissan vehicles, a faulty VVT oil control solenoid on Honda/Mitsubishi, or a failing high-pressure fuel pump on Porsche models.
• Driving with a P1021 code forces the vehicle into 'limp mode,' which caps engine speed at roughly 3,000 RPM and causes $1,500+ in DPF or catalytic converter damage if driven for more than a few miles.
• Before replacing a $300 turbo actuator or $1,500 fuel pump, spend 10 minutes inspecting and cleaning the component's electrical connector with a $10 can of contact cleaner to rule out a simple short.
• For Honda and Mitsubishi owners, check your engine oil level and condition immediately; low or sludgy oil starves the VVT solenoid, triggering P1021 and requiring a $150 solenoid replacement and fresh oil.