P2125 Code: Accelerator Pedal Position Sensor E Circuit
The PCM lost a valid signal from the second, cross-check sensor in the gas pedal.
At a glance
Severity: Moderate
- Meaning
- Accelerator Pedal Position Sensor E Circuit
- System
- Speed & Idle Control · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $60–$450
- DIY difficulty
- Moderate
Sensor E is the second track in the gas pedal. The PCM doesn't use it to drive the throttle directly; it uses it to verify sensor D. P2125 is the general circuit fault for E, stored when its signal drops out, becomes erratic or leaves its valid range in a way the separate low (P2127) and high (P2128) codes don't cover. Diagnosing E means first knowing what it should read, because designs differ: on half-slope pedals E is roughly half of D (about 0.4–0.5 V at rest), on offset pedals such as many Toyotas E sits higher than D (around 1.2–2.0 V at rest), and on mirror-image pedals E starts high and falls as you press. E usually has its own reference and ground, and on some vehicles that reference also feeds other sensors, so a fault elsewhere on that circuit can show up as P2125. With E lost, the PCM can't double-check the pedal and limits power.
Can I keep driving? Drivable with caution; acceleration is limited and may cut back to idle if sensor D also misbehaves. Get it checked soon rather than relying on a single sensor.
How to read P2125
- P Powertrain
- 2 Generic (SAE)
- 1 Fuel & air metering
- 25 Specific fault
Symptoms
- Check engine light, often with a reduced-power message
- Pedal feels normal but acceleration is capped
- Pedal E reading that jumps, drops out or doesn't match the expected ratio to D
- Cruise control switched off while the code is active
- Other 5-volt sensor codes appearing at the same time on some vehicles
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Loose or corroded sensor E terminals in the pedal connector
- Intermittent fault inside pedal sensor E
- Reference circuit shared with another sensor disturbed by that sensor or its wiring
- Harness damage between pedal and PCM
- Moisture in the pedal connector from footwell leaks
- PCM connector or input fault
Diagnosis step by step
Find out what E should read on your vehicle
Look up the pedal sensor specifications for your make before judging any number. Note whether E is half-slope, offset or mirror-image relative to D, and the expected rest and full-pedal values. A reading that looks odd may be perfectly normal for the design.
Tools: OBD-II scanner
Check E against D at three points
Key on, engine off, read D and E at rest, at half pedal and at the floor. Work out whether E matches the expected relationship at each point. A mismatch everywhere suggests a circuit problem, while one that appears at only one position suggests the sensor track.
Tools: OBD-II scanner
Watch the other sensors on E's reference
Use the wiring diagram to see whether E's reference feeds other sensors. Graph E together with one of those sensors and flex the harness. If both glitch together, the fault is in the shared reference or its splice rather than in the pedal.
Tools: OBD-II scanner, Flashlight
Inspect E's terminals at both ends
Unplug the pedal and check E's reference, ground and signal terminals for tension and corrosion, then do the same at the PCM connector if the pedal end looks clean. A terminal that has backed out slightly can pass a test light but still drop out while driving.
Tools: Flashlight, Pliers
Measure E's reference and ground
With the pedal connected and key on, back-probe E's reference and ground. Expect 4.9–5.1 V and less than about 0.1 V respectively. Wiggle the harness while watching the meter to catch an intermittent open.
Tools: Multimeter
Replace the pedal when the circuit proves good
If references, grounds and wiring are sound and the E signal still drops out, replace the pedal module as an assembly. Clear the codes and confirm D and E track together through the full sweep.
Tools: Screwdriver, OBD-II scanner
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean or repin sensor E terminals | No | $60–$200 |
| Repair shared reference splice or damaged harness | No | $120–$380 |
| Replace accelerator pedal module | Yes | $150–$450 |
| Replace another sensor that was disturbing the shared reference | Yes | $80–$350 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
P2125 keeps the check engine light on, which fails an OBD-II emissions inspection. Make sure no other 5-volt sensor codes remain before retesting.
Frequently asked questions
Why does sensor E read so differently from sensor D?
It's designed that way. Giving the two sensors different voltage curves means a single short can't make them both show the same wrong value, so the PCM can always tell when one of them is faulty.
If E is only a check sensor, why does the car lose power?
Without E, the PCM can't confirm that D is telling the truth. Rather than trust an unverified pedal signal, it restricts throttle opening until the fault is fixed.
Can a different sensor cause P2125?
Yes, on vehicles where E shares its 5-volt reference with other sensors. A shorted sensor or chafed wire elsewhere on that circuit drags the reference around and makes E look faulty.
What voltage should sensor E show at rest?
It depends on the design: roughly 0.4–0.5 V on half-slope pedals, around 1.2–2.0 V on offset designs, and well above 3 V on mirror-image pedals. Always compare against the specification for your vehicle.