P0021 on 2014-2019 Chevrolet Silverado 1500: Causes and Fixes for Camshaft Timing

What's Unique About the 2014-2019 Chevrolet Silverado 1500

The Gen V EcoTec3 engines (L83/L86) rely heavily on clean, correct-viscosity oil (specifically SAE 0W-20 dexos1 approved) for the proper function of both the Variable Valve Timing (VVT) and Active Fuel Management (AFM) systems. While P0021 is a VVT code, it can be an early symptom of oil contamination caused by the platform's most notorious issue: AFM lifter failure. When an AFM lifter fails, it can send metallic debris through the oiling system, which then clogs the fine mesh screens on the VVT solenoids, causing them to stick.

Symptoms You May Notice

• Check Engine Light is on
• Rough or unstable idle
• Engine hesitation or stalling, especially at low speeds
• Reduced engine power and poor acceleration
• Decreased fuel economy
• Rattling or knocking noise from the engine on startup

Most Likely Causes

1. Low, Dirty, or Incorrect Viscosity Engine Oil 🔴 High Probability The VVT system is hydraulic and extremely sensitive to oil quality and pressure. These engines specify a Dexos-approved 0W-20 synthetic oil; using thicker oil or extending oil change intervals can lead to sludge that clogs the VVT solenoid passages. Forum users also stress the importance of a quality oil filter (like the OEM ACDelco PF63) with a reliable anti-drainback valve to prevent oil pressure issues at startup.
   How to confirm: Check the oil level on the dipstick. Observe the oil's color and consistency; it should be a translucent amber, not black, thick, or gritty. Check service records for the last oil change date and the type of oil used.
   Typical fix: Perform an engine oil and filter change using the correct OEM-specified full synthetic 0W-20 oil and a quality oil filter (ACDelco PF63 recommended).
   Est. part cost: $40-$80
2. Faulty Bank 2 Intake Camshaft Position Actuator Solenoid 🔴 High Probability → Shop Engine Camshaft This solenoid, also known as an Oil Control Valve (OCV), is the most common part to fail for this code. It is located on the front of the passenger-side cylinder head and is the *top* of the two solenoids. Its internal screens can become clogged with engine debris, or the valve can fail electrically, preventing it from accurately controlling oil flow to the cam phaser.
   How to confirm: Swap the Bank 2 (passenger side) intake solenoid (top) with the Bank 2 exhaust solenoid (bottom). They are identical parts. Clear the codes and drive. If the code changes to P0024 ('B' Camshaft Position - Bank 2), the solenoid is definitively bad. You can also test the solenoid's resistance with a multimeter; it should be between 6.9 and 7.9 ohms at 68°F.
   Typical fix: Replace the Bank 2 intake VVT solenoid. It is held in by a single 10mm bolt and can be replaced in under 15 minutes.
   Est. part cost: $50-$90
3. Wiring or Connector Issue at VVT Solenoid ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness and connector for the Bank 2 intake VVT solenoid. Check for any signs of damage, corrosion, or loose pins. Use a multimeter to check for proper battery voltage at one pin with the key on.
   Typical fix: Repair the damaged wiring or replace the connector pigtail. 🎬 See this walkthrough for replacing the camshaft actuator solenoid valve.
   Est. part cost: $15-$30
4. ECM Software Calibration ⚪ Low Probability In some cases, the Engine Control Module may require an update to prevent false or premature timing codes. Manufacturer Bulletin #N192266190 notes that for certain vehicles, dealers will reprogram the ECM to address conditions where the engine runs rough, stalls, or sets DTCs P0011, P0021, P0014, and P0024.

Rare But Worth Checking

• Failed Camshaft Phaser: → Shop Engine Camshaft If a new solenoid and fresh oil do not resolve the code, the issue may be the mechanical cam phaser itself being stuck due to debris or internal failure. This is a more involved and expensive repair that requires removing the valve cover.
• Stretched Timing Chain or Failed Tensioner: → Shop Engine Timing Chain On higher-mileage engines, a stretched timing chain can cause the actual camshaft position to deviate from the commanded position, triggering this code. This is a major repair.
• Excessive Camshaft End Play: → Shop Engine Camshaft A rare but documented issue where excessive camshaft end play can cause various camshaft position-related trouble codes. GM issued TSB PIP5598A related to this on other engine families, but the principle applies if other causes are ruled out.
• Engine Unit Number (EUN) Discrepancies: A manufacturer service bulletin, Bulletin #PIP5096C, suggests that technicians should inspect the engine EUN sticker for specific sequence markers if P0011, P0014, P0021, or P0024 are found without other drivability concerns.

Diagnosis Steps

1. Check engine oil level and condition. If low, top it off. If dirty or overdue for a change, perform an oil and filter change with full synthetic 0W-20 oil and a quality filter (ACDelco PF63).
2. Clear the code and test drive the vehicle to see if the code returns. If it does not, the issue was likely oil-related.
3. If the code returns, locate the Bank 2 (passenger side) intake VVT solenoid. It is the TOP solenoid on the front of the cylinder head.
4. Inspect the solenoid's electrical connector and wiring for any visible damage, corrosion, or looseness.
5. For a definitive test, swap the intake VVT solenoid (top) with the exhaust VVT solenoid (bottom) on the same cylinder head. They are identical parts and each is held by one 10mm bolt.
6. Clear the codes again and drive the vehicle. If the trouble code changes to P0024 (Exhaust Camshaft Position Timing - Over-Advanced Bank 2), the original intake solenoid is confirmed to be faulty.
7. If the solenoid is bad, replace it with a new part (GM Part #12697161 or equivalent).
8. If the code P0021 returns after the swap, the problem is not the solenoid. Further diagnosis of the wiring, cam phaser, and timing components is required. Check oil pressure with a mechanical gauge.

Parts You'll Likely Need

• Camshaft Position Actuator Solenoid (VVT Solenoid) (OEM #12697161 (Latest), Supersedes: 12688383, 12670340, 12623906) — This is the most common failure point for code P0021. It gets clogged with debris or fails electrically, causing it to stick and create a timing deviation.
  Trusted brands: ACDelco (Recommended), Standard Motor Products (SMP), Delphi
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• Engine Oil Filter and Oil (OEM #ACDelco PF63 (Filter)) — The first and most crucial step in addressing any VVT code is ensuring the engine has clean oil of the correct viscosity (SAE 0W-20). A quality filter is critical.
  Trusted brands: ACDelco (Filter), Mobil 1, Pennzoil, Valvoline
  OEM price range: $40-$80
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0011 — This is the same 'over-advanced' code but for Bank 1 (driver's side). Seeing both P0011 and P0021 together strongly suggests a systemic problem like very low/dirty oil or low oil pressure affecting the entire engine. Bulletin #PIP5568E notes that these codes (P0011, P0014, P0021, P0024) may set together or in pairs during certain drivability concerns.
• P0024 — This is the 'over-advanced' code for the exhaust camshaft on Bank 2. It will appear if the diagnostic step of swapping the intake and exhaust solenoids is performed and the original intake solenoid was the faulty part.
• P0300 — A random/multiple cylinder misfire code. This can be a symptom of the poor engine performance caused by incorrect cam timing. It is also a primary code associated with AFM lifter failure, which can be a root cause of the oil contamination that triggers P0021.

Technical Service Bulletins (TSBs) & Recalls

• TSB 15-06-01-002D/H/O: While not for P0021 directly, this bulletin addresses engine misfires (P0300) and noise from failed AFM lifters, a primary source of oil contamination that can cause P0021.
• TSB 18-NA-355: Addresses the common 8-speed transmission shudder. While unrelated to the engine code, it's a critical TSB for owners of this platform.
• TSB PIP5598A: Discusses crank/no-start conditions caused by a misaligned camshaft reluctor, pointing to potential (though rare) mechanical camshaft issues that could underlie timing codes.
• Bulletin #N192266190 02: Describes a condition where the engine may run rough, run at reduced power, or stall, potentially setting DTCs P0011, P0021, P0014, and P0024.
• Bulletin #PIP5568E: Communicates an investigation into the cause and correction for the group of DTCs P0011, P0014, P0021, and P0024 setting together.

Platform-Specific Known Issues

• Real Owner Experience: Quick Solenoid Fix: A user on gm-trucks.com with a 2016 Silverado 5.3L reported getting code P0021 at 90,000 miles. An oil change did not resolve the issue. They replaced the Bank 2 intake solenoid (top solenoid on the passenger side) with an ACDelco part. The repair took about 15 minutes with a 10mm socket and resolved the code immediately. This is a typical and highly successful repair path reported by many owners.

Mechanic-Grade Diagnostic Values

• VVT Solenoid Resistance — expected: 6.9 to 7.9 ohms at 68°F (20°C).. Failure: A reading that is significantly higher (Mega-ohms), lower, or open indicates a failed coil winding.
• VVT Solenoid Connector Voltage — expected: With Key On, Engine Off (KOEO), one pin should have 12V+ (battery voltage). The other pin is the control circuit, which the ECM provides a pulsed ground to when running.. Failure: No voltage on the power pin indicates a wiring or fuse issue upstream. No pulsed ground signal during operation (checked with a test light or oscilloscope) points to an ECM or wiring problem.
• Engine Oil Pressure (Mechanical Gauge) — expected: Minimum of 24 psi at hot idle. Pressure will rise with RPM, typically to 35-45 psi when cruising. These engines have a two-stage oil pump, so seeing pressure jump to ~60 psi over 3,700 RPM is normal.. Failure: Pressure below 20-22 psi at hot idle is a major concern and can cause VVT and AFM system malfunctions.
• Scan Tool Camshaft Position Variance — expected: Close to 0° when the VVT solenoid is not being commanded.. Failure: A value that is stuck at a high number (e.g., >5°) even when commanded to 0 indicates the phaser is stuck in an advanced position.

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2) or equivalent high-end scan tool: Camshaft Position Actuator Control — This is a bidirectional test used after verifying oil level and pressure. With the engine running at idle, a technician can command the solenoid to a specific duty cycle (e.g., 0% to 100%) and watch the 'Camshaft Position Variance' PID. If the angle changes in response to the command, the solenoid and phaser are likely working. If the angle does not change, it points to a failed solenoid, wiring, or a mechanically stuck phaser.

Wiring & Ground Locations

• G103 — On the front of the passenger side cylinder head, just below the valve cover.. This is a primary engine control ground location for the passenger side (Bank 2) of the engine. While not a common cause for an isolated P0021, a loose or corroded G103 can cause erratic behavior in various Bank 2 sensors and actuators. It's a 'good to check' item if other electrical issues are present.
• VVT Solenoid Connector (Bank 2 Intake) — Front of the passenger side cylinder head, top position. It is a 2-pin connector.. This is the direct connection to the component. Pin 1 is typically ignition voltage (12V+) and Pin 2 is the control wire (pulsed ground) from the ECM. Testing for voltage and signal here is the most direct way to diagnose a wiring or ECM driver issue.

Real Owner Repair Stories

• Forum user on chevytrucks.org (2015 Chevrolet Silverado 5.3L, 110,000 miles) — Check Engine Light with code P0021.
  ❌ Tried (didn't work) Performing an oil and filter change.
  ✅ What actually fixed it The owner swapped the Bank 2 intake and exhaust VVT solenoids. The code changed to P0024, confirming the original intake solenoid was faulty. Replacing the solenoid with a new ACDelco part resolved the issue permanently.
• Shop anecdote from multiple forums and TSBs (2014-2017 Silverado/Sierra 5.3L or 6.2L) — P0021 and/or P0011, sometimes with a startup rattle, followed by P0300 (misfire) and a distinct ticking/knocking noise.
  ❌ Tried (didn't work) Replacing the VVT solenoid often provides a temporary fix or no fix at all.
  ✅ What actually fixed it The root cause was a collapsed Active Fuel Management (AFM) lifter. The lifter failure sent metallic debris throughout the oiling system, which clogged the VVTs solenoid's fine mesh screen, causing it to stick. The ultimate fix required replacing the camshaft, all lifters (often with an AFM-delete kit), and the valve lifter oil manifold (VLOM), along with a thorough engine flush. The P0021 code was merely the earliest, most subtle symptom of this catastrophic failure.
• NHTSA ODI #11694201 — An owner reported receiving error code P0021, indicating "A" camshaft position timing is over-advanced in Bank 2 of the engine. The issue occurred three times before the vehicle was taken to a dealer for inspection.

OEM Part Supersession History

• 12623906, 12670340, 12688383 → 12697161 — Updates typically involve improvements to the internal valve mechanism and the durability of the mesh screens to better resist contamination and clogging.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Active Fuel Management (AFM) Lifter Failure 🔴 High — Very common, can occur as early as 60,000 miles but is frequently seen between 80,000-120,000 miles. Affects cylinders 1, 4, 6, and 7. (Ref: TSB 15-06-01-002 (multiple revisions, e.g., D, H, O) addresses misfires and noises related to AFM lifters.)
• Torque Converter Shudder (8-Speed Transmissions) 🟠 Medium — Widespread on 2015-2019 models with 8L90 and 8L45 transmissions. Often described as driving over rumble strips at 25-80 mph. (Ref: TSB 18-NA-355 recommends a specific transmission fluid flush with Mobil 1 Synthetic LV ATF HP.)
• Cracked A/C Condenser 🟡 Low — Common failure point, leading to loss of refrigerant and A/C function. The condenser is prone to cracking at its welds. (Ref: No specific TSB, but GM has updated the part design to address the weakness.)
• Cracked Radiator 🟠 Medium — The plastic side tanks of the radiator can develop cracks, typically near the upper hose connection, leading to coolant leaks.
• Brake Vacuum Pump Failure 🔴 High — The belt-driven vacuum pump can fail, resulting in a hard brake pedal and significantly reduced braking assist. A recall (N192261970) was issued for some models. (Ref: Recall N192261970)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, a used part is almost never a smart choice. The VVT solenoid is a relatively inexpensive electro-hydraulic part that fails due to internal wear and contamination. A used solenoid from a junkyard carries an unknown history and a high risk of being clogged or failing shortly after installation, wasting time and effort.

What to inspect on the donor part:

• Not applicable, as used parts are not recommended.

OEM-only on this vehicle (don't cheap out):

• VVT Solenoid: While not strictly 'OEM-only', using an ACDelco Genuine GM part is very strongly recommended by professional technicians and forum veterans. Aftermarket solenoids have a high reported failure rate (dead-on-arrival or failing within months).
• Oil Filter: The ACDelco PF63 is specified for its correct 22 PSI bypass pressure and reliable anti-drainback valve. Using an alternative can lead to oiling issues.

Aftermarket brands forum-validated for this vehicle:

• Delphi
• Standard Motor Products (SMP)

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost solenoids from online marketplaces like Amazon or eBay are frequently reported to fail prematurely.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0024 — The 'B' (Exhaust) Camshaft counterpart for Bank 2; often appears during diagnosis if the intake and exhaust solenoids are swapped to test for a component failure.
• P0011 — The Bank 1 equivalent of P0021; often occurs alongside P0021 when oil quality or pressure issues affect both sides of the VVT system.
• P0300 — Random engine misfire code; can be triggered by oil contamination from failed AFM lifters, which also impacts VVT solenoid performance.
• P0521 — Engine Oil Pressure Sensor Performance; related because the VVT system is hydraulic and relies on the same oil pressure and quality required for proper camshaft phasing.

Frequently Asked Questions