P2137 – Throttle/Pedal Position Sensor/Switch “B/C” Voltage Correlation

P2137 is a powertrain diagnostic trouble code that points to a throttle/pedal position signal correlation problem as seen by the engine control system. In practical terms, the Powertrain Control Module (PCM) is comparing two or more related position signals that should agree with each other, and it has detected a mismatch beyond what it considers plausible. Because implementations vary by make, model, and year, you should confirm the exact involved circuits on your vehicle using scan data and basic electrical tests before replacing any parts.

What Does P2137 Mean?

Under SAE J2012 formatting, P2137 is a powertrain code associated with a correlation/plausibility concern between throttle/pedal position signals (often described as a “switch D/E voltage correlation” type of condition in many OEMs). SAE J2012 defines the DTC structure, and standardized descriptions are published in the SAE J2012-DA digital annex; however, the exact sensors/channels labeled “D” and “E” can vary by manufacturer and even by engine family.

This code is shown without an FTB (Failure Type Byte). If your scan tool or OEM service information shows a hyphen suffix (for example, P2137-xx), that suffix is an FTB that further classifies the failure mode (such as signal range/performance, intermittent, or plausibility subtype) while the base code remains a throttle/pedal position signal correlation concern. What makes P2137 distinct is that it’s not simply “high” or “low” voltage; it’s the relationship between signals not tracking correctly.

Quick Reference

• System: Powertrain (electronic throttle/throttle and pedal input plausibility)
• SAE-style meaning: Throttle/pedal position signal correlation outside expected agreement
• What you’ll often notice: Reduced power/limp mode, limited throttle response
• Commonly associated with: Accelerator Pedal Position (APP) sensors, Throttle Position (TP) sensors, electronic throttle body circuits
• Primary diagnostic focus: Compare live data signals and verify 5V reference, ground integrity, and signal plausibility under sweep
• Risk level: Moderate to high (can cause sudden reduced power)

Real-World Example / Field Notes

In the shop, P2137 frequently shows up as an intermittent limp-mode complaint: the vehicle may drive normally until a bump, heat soak, or a specific throttle angle triggers the mismatch. One common pattern is two position signals that agree at idle but diverge during a slow pedal sweep, which points you toward a wiring/connector issue or a worn sensor track rather than a hard power or ground loss. Another pattern is a mismatch that appears only with the engine running and charging voltage up, which can implicate poor grounds, voltage drop on shared sensor returns, or noise on a 5V reference line. The fastest way to avoid a parts cannon is to graph the related position PIDs on a capable scan tool, then confirm with a multimeter or oscilloscope that the signals rise and fall smoothly and maintain a consistent relationship. If the correlation error happens only when you wiggle a harness or tap a connector, you’ve just earned a clear direction for pinpoint testing before considering any sensor or throttle body replacement.

Symptoms of P2137

• Reduced power Engine may enter a limited-throttle or “limp” strategy and feel noticeably weak on acceleration.
• Throttle response Delayed, inconsistent, or “dead spot” response when you press the accelerator pedal.
• Warning lights Check Engine light on; some vehicles may also display an Electronic Throttle Control warning.
• Idle quality Idle may surge, hunt, or feel unstable as the control module questions throttle plausibility.
• Stalling Possible stall when coming to a stop or when transitioning from coast to throttle input.
• High idle Occasionally an elevated idle or “hanging” RPM if throttle angle and commanded torque don’t agree.
• Transmission behavior Harsh or abnormal shifts can occur because engine torque delivery is being limited or derated.

Common Causes of P2137

Most Common Causes

• Throttle/pedal position signal correlation fault due to sensor wear or internal track dropout (commonly associated with Accelerator Pedal Position sensors or Throttle Position sensors, depending on vehicle design).
• Connector issues at the throttle body or accelerator pedal: loose fit, spread terminals, corrosion, water intrusion.
• Wiring harness damage: chafing, pinched loom, intermittent opens, intermittent shorts between the two signal circuits.
• 5-volt reference instability affecting one sensor circuit more than the other (reference pulled down by a fault on a shared reference branch).
• Poor ground integrity (ground offset/voltage drop) causing one signal to be skewed and fail plausibility/correlation checks.

Less Common Causes

• Throttle plate contamination or mechanical binding that makes actual angle lag behind commanded angle enough to fail correlation (more common on high-mileage vehicles).
• Aftermarket accessories or remote-start/alarm splices interfering with pedal/throttle signal integrity.
• Low system voltage or charging system ripple causing erratic sensor outputs under load.
• Engine Control Module (ECM) or Powertrain Control Module (PCM) possible internal processing or input-stage issue, considered only after power/ground, wiring, and sensor signals test good.
• Software/calibration anomalies that require OEM-level confirmation, only after all hardware checks pass.

Diagnosis: Step-by-Step Guide

Tools you’ll want: scan tool with live data and freeze-frame access (plus Mode $06 if available), Digital Multimeter (DMM), back-probe pins or a breakout lead set, oscilloscope (preferred for intermittent dropouts), wiring diagram/service information, battery/charging system tester, basic hand tools for connector inspection, electrical contact cleaner and dielectric grease, and a heat gun or spray coolant (for thermal intermittent checks).

1. Confirm the complaint and record freeze-frame data (RPM, throttle angle, pedal %, vehicle speed, battery voltage). This helps you reproduce the same operating conditions instead of guessing.
2. Verify charging system health: key-on engine-off voltage and running voltage. Excessive ripple or low voltage can distort sensor signals and create false correlation faults.
3. Use the scan tool to view Accelerator Pedal Position and Throttle Position data PIDs side-by-side (names vary by make/model/year). Look for disagreement, sudden jumps, or “flat lines” during a slow pedal sweep.
4. Perform a slow sweep test at idle: press the pedal smoothly from 0–100% and back while watching both redundant sensor signals. A good system shows smooth, predictable changes without spikes or dropouts.
5. Wiggle-test the harness and connectors at the throttle body and pedal while monitoring live data. If the values glitch, you’ve found an intermittent wiring/connector issue to pinpoint.
6. Key off, disconnect the relevant connectors, and do a careful terminal inspection: corrosion, pushed-out pins, spread terminals, water traces, and poor connector latch engagement.
7. With connectors reattached, back-probe and measure the 5-volt reference and ground at the sensor under load. Check for voltage drop on ground (ground offset) and reference sag when you move the harness.
8. If available, use an oscilloscope on the two redundant signal circuits during a pedal sweep. Look for noise, missing sections, or momentary dropouts that a scan tool can average out.
9. If signals and wiring test good but the scan data still shows mismatch, inspect the throttle plate for contamination/binding and verify commanded vs actual throttle response (as supported by your scan tool).
10. Only after all external tests pass, consider a control module issue (possible internal processing or input-stage problem) and confirm PCM/ECM power, grounds, and connector integrity before any module-level decisions.

Professional tip: Correlation faults are often intermittent—if you can’t catch it in the bay, recreate the freeze-frame conditions and use an oscilloscope while doing a harness wiggle and thermal test (warm the suspect connector/harness, then cool it) to reveal momentary signal dropouts that won’t show up as a steady “low” or “high” voltage on a DMM.

Possible Fixes & Repair Costs

Fixes for P2137 must match what you prove with testing: a correlation/plausibility issue between redundant throttle/pedal position signals. Costs vary widely because the root cause can be as simple as a connector problem or as involved as replacing an assembly after wiring checks.

• Low ($0–$80): Battery/charging correction and connector service. Justified when you measure low system voltage, excessive voltage drop on power/ground, corrosion, fretting, or poor terminal tension at the throttle/pedal or Engine Control Module (ECM)/Powertrain Control Module (PCM) connectors, and the fault clears after repair and a road test.
• Typical ($150–$550): Harness repair or sensor/assembly replacement after confirmation. Justified when you find intermittent opens/shorts with wiggle testing, abnormal reference voltage behavior, or one signal track that drops out or doesn’t match the other track on a scope or scan data.
• High ($600–$1,800+): Throttle body or accelerator pedal module replacement plus relearn/calibration (as required by the vehicle) and extended diagnostics. Control module replacement is only justified after all external wiring, powers/grounds, and signal integrity tests pass and you still observe implausible correlation that points to a possible internal processing or input-stage issue.

Labor cost is driven by access (pedal area vs engine bay), intermittent faults that require time to capture, and whether the vehicle requires a relearn procedure after component replacement.

Can I Still Drive With P2137?

You may be able to drive short distances, but you should treat P2137 as a safety-related drivability fault. When the ECM/PCM detects throttle/pedal correlation plausibility problems, it commonly limits throttle response (reduced-power/limp behavior) to prevent unintended acceleration. That can make merging, passing, or climbing grades risky. If the vehicle has unstable idle, severe hesitation, or the throttle response changes unexpectedly, don’t continue driving—tow it and diagnose the electrical signals and power/grounds first.

What Happens If You Ignore P2137?

Ignoring P2137 can lead to recurring reduced-power events, stalling, or unpredictable throttle response under certain vibration/heat conditions, and it can accelerate connector and terminal damage from arcing/fretting if a poor connection is the root cause.

Last updated: February 13, 2026

Vehicles Commonly Affected by P2137

P2137 is commonly seen on many drive-by-wire vehicles across several manufacturers, often reported on GM, Ford, Volkswagen/Audi, and various high-mileage commuter vehicles. The reason is architectural: electronic throttle control uses redundant sensor tracks and strict plausibility monitoring, so small voltage drops, connector fretting, water intrusion, or harness strain can trigger correlation faults. Vehicles with tighter engine bays and higher heat/vibration exposure can be more prone to intermittent signal integrity issues.