P2135 code: Throttle/Pedal Position Sensor A/B Voltage Correlation
P2135 means throttle/Pedal Position Sensor A/B Voltage Correlation. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P2135 means
Electronic throttle and pedal assemblies carry two position sensors ('A' and 'B') that should always agree. P2135 sets when the two disagree beyond a safe margin — the computer no longer trusts the throttle reading. The most common cause is a failing throttle position sensor or throttle body (where both sensors live), but a corroded connector or wiring fault that shifts one signal can do it too. For safety the computer usually drops the engine into reduced-power 'limp' mode until it's resolved.
P2135 symptoms
- Reduced-power or 'limp' mode (limited acceleration)
- Throttle that feels dead, sluggish, or erratic
- Stalling or rough idle
- Check-engine light, often with a warning light
What it costs to fix P2135
Typical range: $50–$600 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Connector / wiring repair | $10–$120 | ~0.5–1.5 hrs |
| Accelerator pedal position sensor | $50–$250 | ~0.3–1 hrs |
| Electronic throttle body | $150–$500 | ~0.5–1.5 hrs |
Always check connectors first — a corroded or loose connector is a cheap, common cause of two sensors disagreeing. If the sensors themselves are at fault, the pedal sensor is usually cheaper than the throttle body.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P2135 for my exact vehicle →
How to fix P2135
Moderate — doable at home with common tools and patience
- Pull codes and freeze-frame data
Note whether P2135 came alone or with companion throttle codes, and what conditions were recorded when it set. An intermittent fault that sets when hot or over bumps points toward a connector or harness problem rather than a dead sensor.
- Inspect both connectors
Unplug the throttle body connector and the accelerator pedal connector and look for green corrosion, bent or spread pins, and water intrusion. A high-resistance pin shifts one sensor's voltage enough to break the A/B correlation — and it's the cheapest possible fix for this code.
- Watch both sensor voltages on a scan tool
Graph TPS A and B (and the pedal sensors) while slowly sweeping the throttle through its range. Both traces should move smoothly in their fixed relationship; a glitch, dropout, or flat spot in one trace identifies which sensor — and which end of the system — is lying.
- Wiggle-test the wiring
With live data still displayed, flex the harness sections between the computer, throttle body, and pedal. If a voltage jumps when you move a particular section, you've located a chafed or broken wire and can repair it instead of replacing parts.
- Replace the faulty unit and relearn
If the glitch traces to the throttle body (where sensors A and B usually live), replace it as a unit; if to the pedal, replace the pedal assembly. Most vehicles then require a throttle relearn — some do it automatically, others need a scan tool — before the limp mode fully clears.
DIY or shop? Connector inspection and cleaning are easy DIY, and a decent scan tool with live graphing lets a patient home mechanic isolate the failing side. The shop advantage shows up at the last step: many vehicles won't come out of reduced-power mode without a proper throttle relearn, which can require an OE-level scan tool. Because this code puts the car in limp mode, don't plan on driving it around while you diagnose in stages — fix it where it sits or have it towed in.
Tools for the DIY steps: OBD2 scanner with live data graphing · Electrical contact cleaner · Multimeter with back-probe pins · Basic hand tools · Dielectric grease
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P2135.
Start a case with P2135 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P2135?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P2135: common questions
Can I drive with P2135?
Whether to keep using the car can't be read from this code alone. It usually triggers reduced-power mode, so acceleration is sharply limited — dangerous when merging or crossing traffic. Get it diagnosed promptly, and have it towed if the pedal barely responds.
What does 'voltage correlation' mean for P2135?
The throttle/pedal system has two sensors that should always read in agreement. P2135 means their voltages no longer correlate — they disagree — so the computer can't trust the throttle position and limits power for safety.
What usually causes P2135?
A failing throttle position sensor or throttle body is common, but a corroded connector or a wiring fault that shifts one sensor's signal is a frequent, cheaper cause. Checking the connectors first can save replacing parts.
How much does it cost to fix P2135?
From a cheap connector/wiring repair to a pedal sensor or a full electronic throttle body. Diagnosis (and checking connectors first) determines which, so you don't replace a good throttle body.
Symptoms that trigger P2135
Drivers who get this code often notice one of these. Each has its own causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P2135 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P2135 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.