P2508

ECM/PCM Power Input Signal High

Q: Is it safe to drive with P2508?

It can be, but overvoltage to the ECM may cause stalling or hard starts and can stress electronics, so have the charging system checked promptly.

Q: Can I just clear P2508?

It returns whenever the ECM sees high supply voltage again. Fix the charging or wiring fault first, then clear.

Computer / power supply Generic OBD-II Medium

What it means

P2508 means the engine computer sees the voltage on its own power-input sense circuit reading higher than expected. Because it concerns the ECM's supply, the usual causes are an overcharging alternator, a bad ground, or corroded power connections. High supply voltage can cause stalling or hard starting, so it's worth diagnosing sooner rather than later.

Medium

Can I keep driving? Often drivable, but because this concerns the ECM's own supply voltage, it can cause stalling, hard starting, or erratic running if the charging system is overcharging.

Real-world scan data

Seen in

175

scans in the past year

Found in

<0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P2508 scans

P0830in 33.7% 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
Possible stalling, hard starting, or intermittent no-start
Erratic running or other electrical codes setting together
Battery/charging warning if the system is overcharging

Common causes

Most likely first

Charging system overvoltage (faulty voltage regulator / alternator)Likely
Poor ground or high-resistance connection at the ECM raising sensed voltageCommon
Corroded or loose ECM power connector or power-relay terminalsCommon
Wiring fault shorting the power-input sense circuit to a higher voltageLess often
Faulty ECM (least likely — rule out the supply first)Less often

How to diagnose & fix

Work through it in order

Measure battery/charging voltage with the engine running; confirm it stays within about 13.5-14.7 V.
If overcharging, test the alternator and voltage regulator.
Inspect and clean the ECM power and ground connections and the main power relay.
Back-probe the ECM power-input sense circuit and compare to actual battery voltage.
Only after supply, grounds, and wiring check out, consider the ECM. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P2508?+

It can be, but overvoltage to the ECM may cause stalling or hard starts and can stress electronics, so have the charging system checked promptly.

Can I just clear P2508?+

It returns whenever the ECM sees high supply voltage again. Fix the charging or wiring fault first, then clear.

Read & clear P2508 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