P2135 on Pontiac: How to Diagnose & Fix
Throttle/Pedal Position Sensor Voltage Correlation
1 Pontiac model · 1 documented issue · 1 critical · $250-$500 repair
P2135 on Pontiac by model: symptoms, diagnosis and fix
G6 owners frequently see a 'Reduced Engine Power' message with the car dropping into limp mode, triggered by throttle position sensor voltage-correlation faults. The throttle body's integrated TPS develops dirty or shorting solder points (sometimes attributed to 'tin whiskers') and corrosion at the connector, so the two throttle sensor signals disagree and the ECM cuts power for safety.
Common Symptoms
- Reduced Engine Power warning message
- Sudden loss of acceleration / limp mode
- Hesitation or rough idle
- Check engine light
How to Fix
Inspect and clean the throttle body and TPS connector; check wiring for corrosion/water intrusion. The common fix is replacing the electronic throttle body assembly; relearn the throttle after replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- GM 19300180 throttle-position sensor kit
Confirm the installed throttle body is the applicable Hitachi design and verify by VIN before purchase.
- GM 12609500 electronic throttle body assembly
2006-2010 Pontiac G6 3.5L or 3.9L as cataloged; confirm VIN, throttle manufacturer and supersession before ordering.
- GM 12615503 electronic throttle body assembly
2007-2009 Pontiac G6 3.6L as cataloged. Does not cover the 2.4L, 3.5L or 3.9L branches.
- GM 12631186 electronic throttle body assembly
2008-2010 Pontiac G6 2.4L; GM catalog supersession may be 12694871. Excludes 2006-2007 2.4L until a VIN-matched catalog path is verified.
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Sources for this issue (3)
P2135 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2135 mean on a Pontiac?
P2135 stands for "Throttle/Pedal Position Sensor Voltage Correlation." P2135 means the powertrain computer detected that the two throttle position (TP) or accelerator pedal position sensors disagree with each other. Drive-by-wire systems use redundant sensors so the PCM can cross-check the throttle or pedal reading for safety; if the two signals don't correlate within an expected range, this code sets. As a fail-safe, the vehicle often enters a reduced-power 'limp' mode, causing sluggish acceleration, a stuck or hesitant throttle, and a warning light. Because it affects throttle control, it should be addressed promptly. On Pontiac it is documented across 1 model: G6.
What are the most common causes of P2135?
The most common causes of P2135 are: Faulty throttle position sensor / throttle body assembly, Faulty accelerator pedal position sensor, Damaged wiring or connectors at the throttle body or pedal, Corroded or loose connector terminals, Poor ground or reference voltage problem, Carbon buildup binding the electronic throttle plate, Failed PCM (rare). The specific cause varies by vehicle.
How much does it cost to fix P2135 on a Pontiac?
Published repair estimates on Pontiac range from $250 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P2135 on a different make?
View P2135 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.