How much does it cost to fix P2135?

DIY repair typically costs $15–$100 for parts. Professional repair runs $200–$750 including parts and labor.

P2135

Powertrain

Moderate

Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation

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Code P2135 is a voltage correlation fault between the two throttle position sensors (A and B) built into your throttle body. Modern electronic throttle bodies use dual sensors for safety — if one fails, the other can still provide a reading. The PCM constantly compares the voltage from sensor A and sensor B. They should always move in a predictable, mirrored relationship. When the two signals don't correlate as expected, this code is triggered.

This is a serious code because it indicates the computer can no longer reliably determine the position of the throttle plate. You'll likely experience sudden loss of power, limp mode, or an inability to accelerate. The engine may surge, stall, or behave erratically. Many vehicles will also illuminate the traction control warning light in addition to the Check Engine Light.

Before replacing the throttle body, start by inspecting the electrical connector — corroded or loose terminals are a very common cause and an inexpensive fix. Also try cleaning the throttle body, as carbon buildup can cause the plate to stick and produce momentary correlation errors. If the connector and cleanliness check out, the throttle body itself likely needs replacement, as the internal sensors cannot be serviced separately on most vehicles.

Severity

High — Immediate AttentionThis Week

Symptoms

•Sudden loss of throttle response while driving
•Engine enters limp mode or reduced power mode
•Erratic or surging idle speed
•Check Engine Light on, possibly with traction control light
•Vehicle may stall or refuse to accelerate

Likely Causes

Failing throttle position sensors in the throttle body35%

The throttle body contains two TPS sensors (A and B) that should produce complementary voltage signals. When one sensor develops a dead spot, drift, or wear, the voltages stop correlating properly and this code is set.

Corroded or damaged throttle body connector30%

The throttle body electrical connector is exposed to engine heat and contaminants. Female terminals can corrode, pull out, or lose tension, creating intermittent contact that causes the A and B signals to disagree.

Wiring harness issues20%

Bare wires shorting to ground, chafed insulation, or damaged pins in the harness between the throttle body and PCM can corrupt one of the two sensor signals, causing a correlation fault.

Carbon buildup causing mechanical binding15%

Heavy carbon deposits on the throttle plate can cause it to stick at certain positions, creating momentary position errors that make the two sensor signals appear uncorrelated to the PCM.