P2135 on Buick: How to Diagnose & Fix
Throttle/Pedal Position Sensor Voltage Correlation
1 Buick model · 1 documented issue · $250-$600 repair
P2135 on Buick by model: symptoms, diagnosis and fix
A failing electronic throttle body or throttle position sensor triggers a 'Reduced Engine Power' message and limp mode, with rough or surging idle and hesitant acceleration. The condition is common enough that GM issued a special coverage adjustment extending the throttle body warranty on some 2009-2011 cars.
Common Symptoms
- 'Reduced Engine Power' message
- Limp mode / very limited acceleration
- Rough or surging idle, RPM jumping
- Hesitation on acceleration
- Check engine light
How to Fix
Clean the throttle body first; if the TPS/electronic throttle body has failed, replace it and perform the required throttle relearn so the computer sets correct idle and full-throttle positions. GM Special Coverage extended this to 10 years / 120,000 miles on covered 2009-2011 models.
Sources for this issue (1)
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 Buick?
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 Buick it is documented across 1 model: Lucerne.
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 Buick?
Published repair estimates on Buick range from $250 to $600 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.