P2127 Code: Accelerator Pedal Position Sensor E Circuit Low
The second gas pedal sensor dropped below its minimum voltage, so the PCM can't verify pedal position.
At a glance
Severity: Moderate
- Meaning
- Accelerator Pedal Position Sensor E Circuit Low
- System
- Speed & Idle Control · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $0–$450
- DIY difficulty
- Moderate
P2127 sets when pedal sensor E falls below the PCM's lower limit, usually a few tenths of a volt. Where on the pedal travel that happens depends on the design, and that's the most useful clue. On half-slope pedals E already rests low, around 0.4–0.5 V, so it has little margin: a slightly low reference or added resistance in the connector can push the rest value under the limit. On mirror-image pedals E is lowest at the floor, so a worn track end or a damaged wire often shows up only at wide-open throttle or kickdown. The freeze frame's pedal position tells you which case you have. Other causes are an open E reference, the E signal shorted to ground, or another sensor on the same reference dragging it down. The PCM then runs on sensor D alone with power held back.
Can I keep driving? The car will usually drive with restricted power. Avoid full-throttle situations such as highway merges until it's repaired, because the car may not respond as expected.
How to read P2127
- P Powertrain
- 2 Generic (SAE)
- 1 Fuel & air metering
- 27 Specific fault
Symptoms
- Check engine light and reduced power
- Fault sets only when flooring the pedal or at kickdown on some vehicles
- On other vehicles it's present from key-on with the pedal at rest
- Pedal E reads near 0 V or well under its specified rest value
- P2138 stored alongside because D and E no longer agree
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Worn or open section of the E track, often at the end of travel
- E reference open, low or dragged down by another sensor on the same circuit
- Corrosion adding resistance in the E reference or signal terminal
- E signal wire shorted to ground
- Pedal connector not fully seated, leaving one E terminal barely touching
- PCM reference or input fault
Diagnosis step by step
Read the freeze frame pedal position
Check the pedal position and engine data stored with P2127. A code set at 0% pedal points to the rest end of the track or a weak reference; a code set near 100% points to the far end of the track, which is typical of mirror-image pedals.
Tools: OBD-II scanner
Measure E at rest against its specification
Key on, engine off, back-probe E's signal and reference at the pedal. If the reference is below about 4.9 V, E drops with it, and a half-slope E can fall under the limit even though the sensor is fine. Fix a low reference before judging the pedal.
Tools: Multimeter
Sweep slowly to the floor
Press the pedal very slowly to the floor while watching or graphing E. On a mirror-image design E should fall smoothly to its lowest specified value. A sudden drop to near zero in the last part of travel means a worn or broken track at that end.
Tools: OBD-II scanner
Check the E signal wire for a short to ground
Disconnect the battery, unplug the pedal and PCM, and measure resistance from the E signal wire to chassis ground. Anything other than an open reading means damaged insulation; look where the harness passes metal edges near the pedal and firewall.
Tools: Multimeter, Flashlight
Unload the shared reference
If E's reference is low with the pedal unplugged, disconnect the other sensors on that reference one at a time while watching the voltage. When it recovers, the last sensor or its wiring was pulling it down.
Tools: Multimeter
Replace the pedal and verify both ends of travel
Once reference, ground and wiring are proven good, replace the pedal module. Verify E at rest and at the floor, and confirm the relationship to D stays constant across 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 |
|---|---|---|
| Reseat and clean the pedal connector | Yes | $0–$120 |
| Replace accelerator pedal module | Yes | $150–$450 |
| Repair E reference or grounded signal wire | No | $120–$380 |
| Replace a sensor that was loading the shared reference | Yes | $80–$350 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Chevrolet | 9 | Malibu Eco, Impala, Camaro | |
|---|---|---|---|
| Jeep | 2 | Patriot, Wrangler | |
| Kia | 2 | Sorento |
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P2127 turns on the check engine light, and an OBD-II emissions inspection fails with the light on. If the fault only sets at full throttle, a few hard accelerations after the repair confirm it's really gone.
Frequently asked questions
Why does P2127 only appear when I floor it?
On pedals where sensor E falls as you press, its lowest voltage is at the floor. A worn track end or a damaged wire there only drops E below the limit at full pedal, so everyday driving never triggers it.
My E reading is 0.45 V at rest. Is that too low?
Not necessarily. On half-slope pedals that's a normal rest value. Compare it with the specification for your vehicle, and check the reference voltage, since a low reference shifts E down with it.
Can I drive with P2127?
Usually yes, gently. The PCM uses sensor D and caps power because it can't cross-check the pedal. Don't count on full acceleration until it's fixed.
Why check other sensors for a pedal code?
On many vehicles the E reference also feeds other sensors. If one of them shorts internally, the shared supply sags and E is the first reading to fall below its limit.