OBD-II trouble code
P2136: Throttle/Pedal Position Sensor 'A'/'C' Voltage Correlation
Two of the throttle body's position sensors — A and C — disagree with each other beyond tolerance, so the computer can't trust the throttle's reported position.
Quick facts
- System
- Powertrain
- Category
- Throttle / Idle
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $650
- DIY difficulty
- Intermediate DIY
What does P2136 mean?
Electronic throttle bodies carry redundant position sensors so the computer can verify the throttle plate is really where it claims. P2136 sets when sensors A and C disagree — their voltages fall outside the fixed relationship they must maintain. It's the same logic as the better-known P2135 (A/B correlation), extended to the third sensor used on some throttle designs and pedal/throttle combinations.
Correlation faults are trust failures, and the electronic throttle system responds firmly: reduced-power mode, capped throttle opening, sometimes a fixed fast idle. The causes are the classic set — carbon buildup mechanically loading the throttle plate so sensors read inconsistently during movement, a failing sensor inside the throttle body, corroded or loose connector terminals skewing one signal, chafed wiring, or an unstable shared 5-volt reference.
Throttle body cleaning plus a careful connector inspection resolves a meaningful share of correlation codes; the rest typically end in a throttle body replacement (the sensors are rarely serviceable separately) followed by the required relearn procedure.
Common causes
- Carbon/sludge buildup binding the throttle plate
- Failing throttle position sensor within the throttle body
- Corroded, loose, or water-damaged connector terminals
- Chafed or shorted wiring between throttle body and PCM
- Unstable shared 5-volt reference
- Worn throttle body gears/motor causing erratic movement
Symptoms
- Check engine light on, often with reduced-power warning
- Limp mode — capped throttle response
- High, fixed, or hunting idle
- Stalling or hesitation
- Possible companion codes P2135/P0121-P0123
Diagnostic steps
- 1.Scan for companion codes; multiple 5-volt-reference codes redirect diagnosis to the reference circuit.
- 2.Graph throttle sensors A and C (and B) on live data through a slow throttle sweep — find where the correlation breaks.
- 3.Inspect the throttle body connector for corrosion, bent pins, and terminal tension.
- 4.Remove the intake boot and inspect/clean the throttle body if carbon-loaded; never force the plate by hand on most designs.
- 5.Check harness sections between throttle body and PCM for chafe.
- 6.Replace the throttle body if a sensor is faulty; perform the throttle relearn and road-test.
Repair cost
$100 – $650
A throttle body cleaning ($100-$200) plus connector service fixes many correlation codes. Replacement throttle bodies run $200-$600 installed on most vehicles, plus a relearn. Wiring repairs land in between — diagnose before replacing.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with throttle body cleaning preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.