P2128

Throttle/Pedal Position Sensor/Switch E Circuit High

Throttle control (drive-by-wire) Generic OBD-II Medium

What it means

P2128 means the ECM sees an abnormally high voltage on the 'E' throttle/accelerator-pedal position sensor circuit — higher than the sensor should ever produce. It usually comes from a short to voltage, an open ground, or a failing sensor. Because the ECM relies on this signal to interpret how far you press the pedal, it may cut the engine to reduced-power mode when the signal can't be trusted.

Medium

Can I keep driving? Often drivable, but the pedal signal may be rejected and the car put into reduced-power mode; repair before relying on it in traffic.

Real-world scan data

Seen in

308

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P2128 scans

P2138in 48.7% of scans

P2122in 40.9% of scans

P2127in 39.0% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Reduced power or 'limp' (failsafe) mode
Poor or unresponsive throttle response to the pedal
Rough or unstable idle

Common causes

Most likely first

Faulty accelerator/throttle position sensor (E element)Likely
Signal wire shorted to voltage or an open in the sensor circuitCommon
Poor connection or corrosion at the pedal/throttle sensor connectorCommon
5-volt reference or ground fault feeding the sensorLess often
Failing ECM/PCMLess often

How to diagnose & fix

Work through it in order

Read freeze-frame data and note related pedal/throttle codes (P2127, P2138).
Inspect the pedal or throttle sensor connector and wiring for damage, corrosion, or a short to power.
With the key on, verify a steady 5-volt reference and good ground at the sensor connector.
Back-probe the E signal circuit and compare readings against spec through pedal travel.
Replace the pedal/throttle position sensor if it reads high or erratic; suspect the ECM only after wiring is confirmed good.

FAQ

Quick answers

Is it safe to drive with P2128?+

Only cautiously — the engine may drop to reduced power with little throttle response, so avoid situations where you need to accelerate quickly until it's fixed.

Can I just clear P2128?+

It will clear, but a high signal from a wiring or sensor fault will set it again, usually quickly.

Read & clear P2128 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX