P2135: How to Diagnose & Fix — Throttle/Pedal Position Sensor Voltage Correlation
28 vehicles · 10 makes · $30-$1,800 repair
How to diagnose and fix P2135: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Jaguar XJ · 2004–2009
This page previously presented one 2004-2009 electronic-throttle-body failure pattern as established fact. The audited official material does not verify that broad cause or model-year scope. It does show a direct safety conflict: NHTSA manufacturer-communication record 10017595 identifies Jaguar bulletin XJ303-10 for the 2004 XJ as “Electronic Throttle Body - Cleaning Prohibited.” Treat throttle symptoms as a reason for model-year-specific diagnosis, not proof that the throttle body needs cleaning or replacement.
How to Fix
Do not follow this page’s former throttle-body cleaning procedure. For a 2004 XJ, Jaguar bulletin XJ303-10 explicitly prohibits electronic throttle-body cleaning. For any model year listed here, have a Jaguar-qualified technician read the stored faults and follow the VIN- and model-year-specific service information before servicing or replacing the assembly. Do not replace the throttle body solely from the symptoms formerly listed on this page.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (1)
Jaguar XK · 2007–2015
The electronic throttle body on the XK develops position sensor failures causing erratic throttle response, limp mode, and check engine lights. The dual-track position sensor wears internally, sending conflicting signals to the engine management system.
Common Symptoms
- Erratic throttle response
- Reduced Engine Power / limp mode
- Check engine light with throttle codes
- Surging idle
- Engine stalling at low speed
How to Fix
Replace the throttle body assembly — the position sensor is not serviceable separately. Recalibrate the throttle position and idle using JLR diagnostic software after replacement. Clean the intake manifold of any carbon deposits during the service.
Owner tips & cautions
- TipKeep a spare throttle body in the trunk if you tour with your XK. It is a 20-minute roadside swap that can get you home instead of waiting for a tow.
Chevrolet Avalanche · 2007–2013
The 2007-2013 Avalanche frequently enters "Reduced Engine Power" mode, severely limiting acceleration. The most common causes are the electronic throttle body wearing out or the accelerator pedal position sensor (APP sensor) developing faults. The vehicle becomes barely drivable in this mode, struggling to accelerate to highway speeds. The issue can occur intermittently before becoming permanent.
Common Symptoms
- "Engine Power Reduced" or "Reduced Engine Power" message on dash
- Vehicle struggles to accelerate past 20-30 mph
- Check engine light with P2128 or P2138 codes
- Intermittent power loss that resolves after restart
- Rough or hesitant throttle response
How to Fix
Diagnose with a scan tool to determine if the throttle body or accelerator pedal position sensor is the cause. Throttle body replacement costs $200-$400 parts and labor. APP sensor replacement costs $100-$250. A remanufactured throttle body from a quality source works well. Clear codes after repair and road test to verify.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
$20–$40View
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (2)
Ford F-150 · 2004–2004
Ford Transit · 2015–2019
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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?
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.
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?
Repair costs for P2135 range from $30 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by P2135?
Au7o has documented P2135 across 28 vehicle models from 10 manufacturers: Buick, Cadillac, Chevrolet, Chrysler, Ford, GMC, Jaguar, Nissan, Pontiac, Volvo.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.