OBD-II trouble code
P2137: Throttle/Pedal Position Sensor 'B'/'C' Voltage Correlation
Throttle position sensors B and C disagree beyond tolerance — the redundancy cross-check failed, so the computer limits throttle authority.
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
Browse every code in P2100–P2199, or start from the full code library.
What does P2137 mean?
P2137 completes the throttle correlation family: sensors B and C — two of the redundant position signals in the electronic throttle system — have fallen out of their required voltage relationship. Together with P2135 (A/B) and P2136 (A/C), it tells you not just that a correlation failed but which pair, which helps triangulate: a sensor implicated by two pair-codes at once (say, C in both P2136 and P2137) narrows the fault to that one channel, while the pair that still agrees tells you the other two signals are tracking each other correctly. The channel is the sensor element plus its own wire and pin, though, not the element alone.
The fault menu is largely that of its siblings — connector corrosion skewing one signal, chafed wiring, a sagging shared 5-volt reference, or a failing sensor inside the throttle body — with one exclusion worth stating plainly, because it is the stock answer to throttle complaints generally and it is not an answer to this one. Carbon on the throttle plate does not break sensor-to-sensor correlation. Both position sensors ride the same throttle shaft, so a plate that sticks or binds carries both of them with it and leaves their voltage relationship intact; what carbon sets is a performance code about where the plate ended up, not a correlation code about two signals disagreeing. If cleaning a throttle body ever appears to clear a correlation code, something else was disturbed while doing it, and a connector is the usual candidate. The system response is the same firm one — reduced-power mode and capped throttle opening until the signals agree.
Graphing all throttle sensor voltages through a slow sweep is the decisive test. Most confirmed sensor failures end in throttle body replacement plus the relearn procedure, since individual sensors are rarely sold or serviceable.
Common causes
- Corroded or loose connector terminals skewing one signal
- Water intrusion at the throttle body connector
- Chafed or shorted wiring between throttle body and PCM
- Unstable shared 5-volt reference, which tends to disturb more than one pair at once
- Failing throttle position sensor, which on most designs means replacing the throttle body as an assembly
Symptoms
- Check engine light with reduced-power warning
- Limp mode / capped acceleration
- Erratic, high, or hunting idle
- Hesitation or stalling
- Companion correlation codes (P2135/P2136) in many cases
Diagnostic steps
- 1.Note all correlation codes present — the sensor common to two pair-codes is the prime suspect.
- 2.Graph all throttle position sensor voltages through a slow sweep; identify which signal departs from spec.
- 3.Inspect the throttle body connector for corrosion, moisture, and terminal tension.
- 4.Check the shared 5-volt reference for stability, especially if unrelated sensor codes coexist.
- 5.Wiggle-test the throttle body connector and its harness with the voltages still graphed. A skew that appears only while the loom is moved is a terminal or a conductor, not a sensor.
- 6.Replace the throttle body if a sensor is confirmed bad; perform the relearn and verify with a road test.
Repair cost
$100 – $650
Same repair economics as P2135/P2136: cleaning and connector work at the low end ($100-$200), throttle body replacement at $200-$600 installed plus relearn. Which pair-code you have doesn't change the cost — it changes which sensor you suspect first.
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.