P2135
Throttle/Pedal Pos Sensor/Switch A / B Voltage CorrelationP2135 is a generic OBD-II powertrain diagnostic trouble code: Throttle/Pedal Pos Sensor/Switch A / B Voltage Correlation. It is logged by the engine control unit when the throttle monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P2135 means
P2135 is set when the PCM/ECM detects that the voltage signals from Throttle Position Sensor (TPS) A and Throttle Position Sensor B on a drive-by-wire (electronic throttle control) system do not correlate within the expected tolerance. Modern ETC systems use two TPS sensors built into the throttle body that operate on opposing voltage curves — as one signal rises from approximately 0.5 V at closed throttle to ~4.5 V at wide-open throttle, the other mirrors it in reverse. The PCM continuously compares these two signals; if their combined voltage deviates outside the calibrated window (typically more than ~0.2–0.5 V of divergence) for a set period, P2135 is stored and the MIL illuminates.
Because the throttle position is the primary input for torque delivery in a drive-by-wire system, a correlation fault is treated as a safety-critical condition. The ECM will typically command a reduced-power or limp-home mode — limiting engine output to a low fixed throttle opening (often around 10–15%) — to prevent uncontrolled acceleration while still allowing the vehicle to be driven to safety. In some implementations the throttle may close completely, causing stalling or a no-start condition.
P2135 is an SAE generic code present across most makes and models with electronic throttle control. It is closely related to individual TPS circuit codes (P0120–P0123, P0220–P0223) but specifically flags a correlation disagreement between the two sensors rather than an out-of-range voltage on either circuit alone. GM, Nissan, and Toyota platforms are particularly known for this fault, sometimes addressed by manufacturer technical service bulletins.
Common causes
Most-frequently reported root causes when P2135 is logged.
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1
Faulty throttle position sensor (TPS A or B) inside the throttle body assembly
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2
Worn or contaminated throttle body causing erratic sensor output
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3
Corroded, loose, or damaged connector pins at the throttle body harness plug
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4
Chafed, shorted, or broken wiring in the TPS signal or 5 V reference circuits
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5
Failed or sticking electronic throttle body (mechanical binding affects sensor agreement)
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6
Faulty accelerator pedal position (APP) sensor feeding incorrect demand signal to PCM
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7
Water intrusion or contamination in the throttle body connector
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8
PCM/ECM internal fault affecting TPS signal processing (rare)
Symptoms drivers notice
How to diagnose P2135
A typical diagnostic flow when this code is present.
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1
Scan for all stored DTCs and freeze-frame data; note any companion TPS/APP codes (P0120–P0123, P0220–P0223) that help isolate which sensor or circuit is at fault
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2
Inspect the throttle body harness connector for corrosion, bent pins, moisture, or loose fit; clean contacts and re-check
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3
With ignition ON (engine off), use a scan tool to monitor live TPS A and TPS B voltage: at closed throttle one should read ~0.5 V and the other ~4.5 V; sweep the throttle by hand and verify signals move smoothly and inversely
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4
Measure the 5 V reference supply and signal ground at the throttle body connector with a multimeter; reference must be 4.8–5.2 V and ground must be below 0.1 V
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5
Check wiring continuity and insulation between the PCM and throttle body for shorts to ground, shorts to voltage, or high resistance (spec: <1 Ω per circuit)
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6
Manually rotate the throttle plate and check for binding, carbon build-up, or rough movement that could cause the two sensors to disagree; clean or replace throttle body as needed
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7
If wiring and connector checks pass and live data still shows correlation divergence, replace the throttle body assembly (TPS sensors are typically non-serviceable individually); clear codes and verify repair with a full drive cycle
Related powertrain codes
- P0120 — Throttle Position Sensor/Switch A Circuit Malfunction
- P0121 — Throttle Position Sensor/Switch A Circuit Range/Performance Problem
- P0122 — Throttle Position Sensor/Switch A Circuit Low Input
- P0123 — Throttle Position Sensor/Switch A Circuit High Input
- P0124 — Throttle Position Sensor/Switch A Circuit Intermittent
- P0220 — Throttle/Pedal Position Sensor/Switch B Circuit Malfunction
Frequently asked questions
Can I drive my car safely with a P2135 code active?
Only for a short distance to reach a repair shop. The vehicle will typically enter limp-home mode with severely restricted throttle response, making highway driving dangerous. In some cases the engine may stall entirely. Have it diagnosed and repaired as soon as possible.
Will clearing the code fix the problem?
Clearing the code removes the MIL temporarily, but if the underlying fault remains the code will return — often within the same drive cycle. Clearing without repairing the root cause can also erase valuable freeze-frame data needed for diagnosis.
Why are both TPS sensors needed, and why must they agree?
Drive-by-wire throttle bodies use two sensors with opposing voltage curves as a safety redundancy: if one sensor fails or produces an out-of-range voltage, the PCM can detect the disagreement and shut down the throttle rather than risk uncontrolled acceleration. The SAE specification requires their combined output to stay within a defined window at all times.
Is P2135 more common on certain vehicles?
Yes. General Motors vehicles (particularly 2007–2014 Silverado, Sierra, Tahoe, and Suburban with the 4.8/5.3/6.0 L V8) and Nissan/Infiniti models (VQ and VK engine platforms) have well-documented prevalence of this code. GM issued several TSBs recommending throttle body replacement. Toyota and Lexus ETC-equipped models are also commonly affected.
Disabling P2135 in software
RaceTune can permanently disable P2135 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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