P2135 — Throttle/Pedal Position Sensor/Switch “A”/”B” Voltage Correlation #

Note: The wording of this code may vary depending on the manufacturer.

• Throttle/Pedal Position Sensor/Switch “A”/”B” Voltage Correlation (General/GM/Ford)
• Throttle/Pedal Position Sensor A/B Voltage Mismatch (Toyota)
• Throttle Position Sensor Voltage Correlation Error (Nissan)
• Accelerator Pedal Position Sensor Range/Performance (Hyundai/Kia)

Summary of Code P2135 #

P2135 is a generic powertrain code triggered when the engine control module (ECM) or powertrain control module (PCM) detects a mismatch between the voltage signals from Throttle Position Sensor (TPS) “A” and “B” or the Accelerator Pedal Position (APP) sensors. These sensors monitor the position of your gas pedal and throttle plate, ensuring the engine receives the correct amount of air for smooth operation. When their outputs don’t agree within a set threshold, the ECM/PCM suspects a fault and sets P2135. This code is commonly associated with drive-by-wire systems, where there is no mechanical linkage between the accelerator pedal and the throttle. An illuminated check engine light often follows, along with potential engine performance issues.

Frequent Symptoms for Code P2135 #

When P2135 is present, your vehicle may exhibit noticeable and sometimes sudden changes in drivability. The engine computer may enter a “limp mode” to protect the engine and ensure safety. Here are the most common symptoms:

• Check Engine Light (CEL) illuminated
• Reduced engine power or limp-home mode
• Poor throttle response (delayed or erratic acceleration)
• Stalling at idle or while driving
• Unstable idle speed (fluctuating RPMs)
• Hard starting or no-start condition

Probable Causes for P2135 (in order of likelihood) #

Several factors can trigger a P2135 code, but some are more common than others. Most often, the issue relates to the sensors themselves or their wiring, but sometimes the problem lies with the electronic throttle body or the vehicle’s ECM/PCM.

1. Faulty Throttle Position Sensor (TPS) or Accelerator Pedal Position (APP) sensor
2. Wiring problems (damaged, corroded, or loose connectors/circuits between sensors and ECM/PCM)
3. Defective throttle body assembly (especially electronic throttle bodies)
4. ECM/PCM software update required or internal ECM/PCM fault
5. Contaminated throttle plate causing abnormal readings
6. Aftermarket accessories/interference affecting sensor signals

Step-by-Step Diagnosis for Code P2135 #

Diagnosing P2135 demands a methodical approach to avoid unnecessary parts replacement. Here’s a trusted step-by-step process:

1. Scan for codes: Use an OBD-II scanner to confirm P2135 and check for related codes (P0120, P0220, P2101, etc.).
2. Visual inspection: Examine wiring and connectors at the throttle body and accelerator pedal for damage, corrosion, or loose pins.
3. Check live data: With a scan tool, monitor TPS and APP sensor voltages—both should change smoothly and in sync as you press/release the pedal.
4. Test sensors individually: Using a multimeter, measure TPS/APP sensor voltages at rest and at wide-open throttle. Compare readings to OEM specifications.
5. Inspect the throttle body: Look for carbon buildup or sticking throttle plate. Clean if necessary.
6. Wiggle test: While monitoring the sensor values, gently wiggle wire harnesses/connectors to check for intermittent faults.
7. Check for technical service bulletins (TSBs): Some manufacturers have known fixes or software updates for this code.

Possible Repairs for P2135 #

Repairs should always address the root cause. Here are the most effective solutions, based on the diagnosis:

• Replace faulty TPS or APP sensor if out-of-spec or intermittent
• Repair or replace damaged wiring/connectors between sensors and ECM/PCM
• Replace throttle body assembly (if internal sensor or motor failure is suspected and not serviceable separately)
• Clean throttle plate and bore to ensure smooth movement and accurate readings
• Update ECM/PCM software if a TSB applies to your vehicle
• Replace ECM/PCM in rare cases where it’s confirmed to be faulty

Can You Drive with Code P2135? #

Limited: You may be able to drive short distances, but it is not recommended. P2135 often triggers reduced engine power mode, which severely limits acceleration and top speed for safety reasons. If the engine stalls or the throttle response is unpredictable, continued driving could be dangerous. Address the code as soon as possible to avoid unsafe situations or further vehicle damage.

Vehicles Most Commonly Affected by P2135 #

This code is especially prevalent on vehicles using electronic throttle control systems. The following makes/models frequently experience P2135 due to known sensor or throttle body issues:

• Chevrolet Silverado, Tahoe, Suburban (especially 2007–2014)
• GMC Sierra, Yukon
• Cadillac Escalade
• Toyota Camry, Corolla, Tacoma
• Nissan Altima, Sentra, Maxima
• Hyundai Sonata, Elantra
• Ford F-150, Fusion

Common Mistakes & Best Practices with P2135 #

Even seasoned techs can slip up with this tricky code. Avoid these pitfalls and follow these golden rules:

• Do not replace the throttle body or ECM/PCM without confirming the diagnosis
• Always inspect wiring/connectors first—many P2135 cases are caused by simple electrical faults
• Use a scan tool to verify sensor data before replacing any parts
• Check for TSBs or recalls—sometimes a software update or revised part is the correct fix
• Clear codes after repairs and test drive to ensure the issue is resolved

Express FAQ for Code P2135 #

Q: Can cleaning the throttle body fix P2135?
A: In some cases, yes—especially if carbon buildup is causing the throttle plate to stick or sensors to misread. Always clean with appropriate products and procedures.

Q: Is P2135 always a sensor failure?
A: No, while faulty sensors are common, wiring faults and connector issues are equally likely. Don’t skip a thorough visual and electrical inspection before replacing expensive parts.