P0222 on 2017-2020 Genesis G80 3.8L: Throttle Position Sensor 'B' Circuit Low Causes and Fixes

What's Unique About the 2017-2020 Genesis G80

On the Genesis G80 and other Hyundai/Genesis vehicles with the Lambda V6 engine, the throttle position sensors (TPS) are integrated directly into the electronic throttle body assembly. They are not available as separate, replaceable parts. Therefore, when a P0222 code points to an internal sensor failure, the entire throttle body unit must be replaced. While wiring issues are possible, a failed sensor within the assembly is the most common point of failure for this specific code on this platform.

Symptoms You May Notice

• Check Engine Light is illuminated
• Reduced engine power or 'limp mode'
• Hesitation or stumbling during acceleration
• Unresponsive or delayed throttle response
• Rough or unstable idle
• Engine may stall
• Poor or no acceleration

Most Likely Causes

1. Faulty Electronic Throttle Body Assembly 🔴 High Probability → Shop Fuel Injection Throttle Body The throttle position sensor is a known wear item, and on this platform, it is integrated into the throttle body assembly, which must be replaced as a unit. This is the most common resolution for P0222 on the Lambda II engine family.
   How to confirm: Using a scan tool, observe the live data for TPS Sensor 1 and TPS Sensor 2. With the key on and engine off, press the accelerator. The voltage for one sensor should rise while the other falls. If Sensor 'B' voltage is stuck low (e.g., <0.5V) and does not change, the assembly is faulty. The ECM may set the code if the voltage is detected below 0.25V for more than 0.1 seconds.
   Typical fix: Replace the entire electronic throttle body assembly and the corresponding gasket. A throttle relearn procedure may be required after installation, though many Hyundai/Genesis vehicles will relearn automatically with a few drive cycles or a manual key-cycling procedure. 🎬 See: Genesis 3.8 throttle cleaning and reset walkthrough
   Est. part cost: $250-$500
2. Dirty or Sticking Throttle Body 🟡 Medium Probability → Shop Fuel Injection Throttle Body Gasoline Direct Injection (GDI) engines, like the Lambda II, are prone to carbon buildup in the intake system. This accumulation can cause the throttle plate to stick or move slowly, leading to sensor correlation errors that trigger a P0222 code.
   How to confirm: Remove the air intake hose from the throttle body and visually inspect the throttle plate and bore for significant black carbon deposits.
   Typical fix: Clean the throttle body bore and plate thoroughly with a dedicated throttle body cleaner and a soft brush. Do not push the plate open with your fingers; have an assistant turn the key to 'ON' and press the gas pedal to open it electronically.
   Est. part cost: $10-$20
3. Wiring Harness or Connector Issue ⚪ Low Probability Engine vibrations and heat can, over time, cause wires to fray or pins in the connector to lose contact. A short to ground in the signal circuit is a possible cause.
   How to confirm: Visually inspect the wiring harness leading to the throttle body for any signs of chafing, melting, or corrosion. Check that the connector is seated securely. A 'wiggle test' on the harness while monitoring sensor voltage can reveal an intermittent connection. Use a multimeter to check for a steady 5V reference signal and good ground at the connector.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the electrical connector pins.
   Est. part cost: $5-$50

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare. The PCM should only be considered as the cause after all other possibilities, including the throttle body and wiring, have been definitively ruled out.

Diagnosis Steps

1. Connect an OBD-II scanner and confirm P0222 is the primary code. Note any other codes, such as P0122, P2106, or P2110.
2. Visually inspect the electrical connector and wiring harness at the throttle body. Look for loose connections, corrosion, or any signs of damage like chafing or melting.
3. With the key on and engine off, use the scanner's live data function to monitor the voltages of TPS1 ('A') and TPS2 ('B').
4. Have an assistant slowly press and release the accelerator pedal. The two voltage readings should move smoothly in opposite directions. If the 'B' sensor voltage is stuck low (e.g., below 0.5V) or doesn't respond, the fault is likely internal to the throttle body.
5. If the sensor readings seem erratic, perform a 'wiggle test' on the wiring harness while watching the live data to check for an intermittent short or open circuit.
6. Remove the intake duct and inspect the throttle body for heavy carbon buildup. If dirty, clean it as a first step, as this can cause the plate to stick.
7. If the wiring is confirmed to be good and cleaning the throttle body does not resolve the issue, the electronic throttle body assembly is faulty and requires replacement.

Parts You'll Likely Need

• Electronic Throttle Body Assembly (OEM #35100-3CAC0) — This is the most common failure for code P0222, as the internal throttle position sensor fails and is not sold separately. The original part 35100-3CAC0 has been superseded by part number 35100-3CAC0--DS. Always verify with VIN.
  Trusted brands: Hyundai/Genesis Genuine, Bosch
  OEM price range: $350-$500
  Aftermarket price range: $250-$400
• Throttle Body Gasket (OEM #35101-3C000) — The gasket should always be replaced when the throttle body is removed to prevent vacuum leaks.
  Trusted brands: Hyundai/Genesis Genuine
  OEM price range: $7-$15
  Aftermarket price range: $5-$10

Related Codes That Often Appear With This One

• P0122 — This code is for 'Throttle Position Sensor 'A' Circuit Low'. Seeing both codes together strongly suggests a problem with the throttle body assembly itself or its electrical connector, affecting both internal sensors.
• P2106 — This code means 'Throttle Actuator Control System - Forced Limited Power'. It is an informational code set by the ECM to indicate it has entered 'limp mode' as a direct result of the critical fault detected by P0222.
• P2110 — This code means 'Throttle Actuator Control System - Forced Limited RPM'. Similar to P2106, it's a failsafe code indicating the ECM is actively limiting engine speed due to the P0222 fault.

Technical Service Bulletins (TSBs) & Recalls

• Hyundai TSB 12-FL-003: While not for P0222 specifically, it provides the official manufacturer procedure for cleaning Electronic Throttle Control (ETC) systems due to carbon buildup, which can be a contributing cause.
• Hyundai TSB 23-EM-007H: This TSB provides a general procedure for combustion chamber cleaning on Hyundai/Genesis GDI engines. This is relevant as heavy carbon buildup on intake valves and the throttle body is a known issue that can contribute to throttle plate sticking and related codes like P0222.

Platform-Specific Known Issues

• Owner Experience: Intermittent Limp Mode: An owner of a 2017 G80 3.8L on a Reddit forum described experiencing sudden rough upshifts at low speeds, like a 'kick in the butt', which started around 68,000 miles. Another user with a 2020 G80 3.8L reported having the entire transmission replaced at 40,000 miles for a similar issue that persisted even after the replacement. While not directly linked to a P0222 code in the thread, these symptoms (limp mode, erratic behavior) are consistent with throttle body failure and highlight the electronic complexities of the platform.

Mechanic-Grade Diagnostic Values

• TPS 'B' (TPS2) Signal Voltage — expected: Decreases from a high value towards 0.5V as the throttle opens. It operates inversely to TPS1.. Failure: Voltage is stuck below 0.25V for more than 0.1 seconds.
• TPS 'A' (TPS1) Signal Voltage — expected: Rises smoothly from ~0.3-1.0V (closed) to ~4.2-4.8V (fully open).. Failure: Voltage is erratic, does not respond, or is outside the expected range.

Scan Tool Commands That Help

• Hyundai GDS (or equivalent advanced scanner): Active Test: ETC Motor — This bidirectional command allows a technician to force the Electronic Throttle Control (ETC) motor to open and close, typically for one-second intervals. It's used to visually and audibly confirm if the throttle plate and motor are physically responding to commands, helping to isolate a mechanical jam from an electrical sensor failure.
• Hyundai GDS (or equivalent advanced scanner): Throttle Reset / Throttle Matching — This function is used after replacing the throttle body or cleaning it. It forces the ECU to relearn the closed, open, and intermediate positions of the new or cleaned throttle plate, ensuring accurate idle and throttle response.

Wiring & Ground Locations

• Engine Ground Strap — On the Lambda 3.8L engine, a primary ground strap is typically located on an engine mount, often on the driver's side of the engine bay. Another key ground point is on the intake manifold itself.. A poor engine ground can introduce electrical noise or voltage drops, affecting the sensitive 5V reference circuits used by sensors like the TPS. Ensuring these grounds are clean and tight is a crucial step in diagnosing intermittent or unexplained low voltage codes like P0222.
• ECM/PCM Ground — On similar Hyundai/Genesis platforms, a key ground point for the ECM is designated as 'GHG01' or 'GHG02' and is located on the chassis in the left rear of the engine compartment.. The ECM provides the ground for the TPS circuit. If the ECM's own ground connection to the chassis is compromised, it can cause the reference voltage seen by the sensor to be incorrect, potentially triggering a 'Circuit Low' fault.

Real Owner Repair Stories

• hyundai-forums.com user report (paraphrased) (2017 Hyundai Tucson 2.0L (similar platform electronics)) — Intermittent limp mode, especially in hot weather. Codes P0222, P0122, and P2135 would appear. Restarting the car would temporarily fix the issue.
  ❌ Tried (didn't work) Thoroughly cleaning the throttle body.
  ✅ What actually fixed it The entire electronic throttle body assembly was replaced, which permanently resolved all codes and symptoms.

OEM Part Supersession History

• 35100-3CAC0 → 35100-3CAC0--DS — The reason for the supersession is not officially documented, but it typically indicates a revision to address a known issue, improve durability, or change suppliers.
  Heads up: The new part number 35100-3CAC0--DS directly replaces the original 35100-3CAC0 and should be fully compatible.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• ABS Module Electrical Short 🔴 High — Common enough to trigger a major safety recall (NHTSA 21V160000) for 2017-2020 G80 models. (Ref: Recall 21V160000: The ABS module can malfunction and short circuit, increasing the risk of an engine compartment fire while parked or driving. Owners were advised to park outdoors until the recall fix (fuse replacement) was performed.)
• Carbon Buildup on Intake Valves 🟠 Medium — A common issue for most GDI engines, including the Lambda II 3.8L. Typically requires cleaning between 80,000 and 120,000 miles to prevent misfires and performance loss. (Ref: TSB 23-EM-007H provides a general procedure for combustion chamber cleaning.)
• Potential for Oil Consumption 🟠 Medium — Anecdotal reports suggest some Lambda II engines may begin to consume oil, often past 100,000 miles. While not universal, it's a known possibility that can lead to other issues if the oil level is not monitored. (Ref: TSB 23-EM-008H provides guidelines for inspecting and diagnosing oil consumption concerns.)
• Harsh Shifting / Transmission Issues 🟠 Medium — Owners have reported rough or delayed shifting, particularly at low speeds. Some cases have required transmission replacement at relatively low mileage (40k-70k miles). (Ref: A TSB for older Genesis models (15-AT-003) addressed harsh upshifts by replacing solenoids, indicating a history of transmission control issues in the family line.)
• Starter Solenoid Water Intrusion 🔴 High — A recall was issued for 2017-2019 G80 models because water could enter the starter solenoid, causing an electrical short and potential fire risk. (Ref: Recall Campaign 012G (related to NHTSA ID 24V107000) addresses this issue.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used throttle body can be a cost-effective option if sourced from a low-mileage, reputable salvage yard, especially given the high cost of a new OEM part. Since the failure is electronic wear, a part from a rear-ended vehicle with low mileage is a good candidate.

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

What to inspect on the donor part:

• Verify the donor vehicle's mileage. Aim for under 60,000 miles if possible.
• Inspect the electrical connector pins for any corrosion, bending, or damage.
• Check the throttle bore for excessive carbon buildup. While it can be cleaned, heavy buildup may indicate a hard life.
• Ensure the part number matches your original part or its superseded version (35100-3CAC0--DS).
• Ask for a warranty, even if it's only 30-90 days, to protect against an immediate failure.

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

• Electronic Throttle Body Assembly: While some aftermarket options exist (like Bosch, who may be the OEM supplier), this is a critical electronic component. A genuine Hyundai/Genesis part or a used OEM part is the safest bet to avoid compatibility or premature failure issues.

Aftermarket brands forum-validated for this vehicle:

• Bosch (Often the original equipment manufacturer for European and Korean brands)

Brands owners have reported issues with on this vehicle:

• No-name, unbranded parts from online marketplaces should be avoided, as their internal electronics may not meet OEM specifications for voltage accuracy and longevity.

Real Owner Stories

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

Related OBD-II Codes

• P0122 — Often appears alongside P0222 as a primary code during diagnosis; relates to low voltage in the Throttle Position Sensor 'A' circuit.
• P2106 — A companion code indicating the Electronic Throttle Control (ETC) system has forced limited power (limp mode) due to the P0222 fault.
• P2110 — Indicates the Electronic Throttle Control system is limiting engine RPM, frequently triggered by sensor correlation issues in the throttle body.

Frequently Asked Questions