P2138
UniversalThrottle/Pedal Position Sensor/Switch D/E Voltage Correlation.
The engine controller compares voltage signals from throttle or pedal position sensor circuits D and E to check that they correspond as expected. P2138 means the signals do not correlate. These signals help the vehicle control throttle response, so the condition may cause reduced power, unusual acceleration response, or a warning light. The code does not by itself prove that a sensor needs replacement.
⚠️ Before You Begin (Safety First)
If acceleration becomes unpredictable, the engine loses power, or the vehicle is difficult to control, pull over safely and arrange assistance rather than continuing to drive. If the vehicle responds normally, have the fault diagnosed promptly and drive cautiously; exact guidance depends on the vehicle.
Common Symptoms
- The check-engine or electronic throttle warning light may come on because the controller has detected disagreement between the D and E signals.
- Reduced engine power or a limited-power mode may occur if the controller limits throttle operation in response to the signal mismatch.
- Acceleration may be delayed, uneven, or inconsistent if the controller cannot reliably interpret the position signals.
- The engine may hesitate or stall in some circumstances if the detected fault affects engine control.
- There may be no noticeable symptoms apart from a stored code or warning light.
Common Causes
- A fault in one of the D or E sensor/switch signal circuits, such as an intermittent or out-of-range signal.
- Loose, damaged, corroded, or contaminated connectors affecting a sensor circuit.
- Damaged wiring, a poor electrical connection, or a fault in a shared power or ground circuit.
- A throttle or pedal position sensor assembly fault, if testing confirms the signal itself is faulty.
- A control-module or related circuit fault, considered only after wiring and sensor checks.
Diagnostic Steps
- Note warning lights and any changes in acceleration or power. If throttle response is unpredictable or control is affected, stop driving when safe and arrange assistance.
- With the vehicle off, visually check accessible throttle- and pedal-related wiring and connectors for looseness, visible damage, or corrosion. Do not force connectors or probe terminals.
- If a compatible scan tool is available, record this and any related codes before clearing anything; related codes can help identify whether the issue is limited to one circuit or part of a wider electrical fault.
- Avoid replacing a sensor based on the code alone. If the fault returns or symptoms are present, arrange vehicle-specific electrical testing and scan-data comparison.
When to Call a Professional
A technician can review related codes and scan data, compare the D and E signals while the pedal or throttle is operated, and test the relevant wiring, connectors, power supply, and grounds. The sensor or control module should be considered only after circuit checks and vehicle-specific procedures support that diagnosis.
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Commonly Asked Questions
Does P2138 prove the pedal or throttle sensor is faulty?
No. It identifies a voltage-correlation problem between circuits D and E. Wiring, connectors, power or ground issues, and other circuit faults can also cause the signals to disagree.
Can I drive with P2138?
It depends on how the vehicle behaves. If acceleration is unpredictable, power is severely limited, or the vehicle is difficult to control, stop when safe and arrange assistance. If it behaves normally, drive cautiously and seek diagnosis promptly.
Why might the vehicle have reduced power?
The controller may limit throttle operation when it cannot rely on the position signals. The exact response varies by vehicle.
What should be checked before replacing a sensor?
Check related codes and scan data, then inspect and test the relevant connectors, wiring, power, and grounds using procedures for the specific vehicle.
Browse Available Code Guides
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