P2505
ECM/PCM Power Input Signal
ECM power supply
Generic OBD-II
High
What it means
P2505 means the ECM has detected a problem with its own power input — the voltage feeding the engine computer is missing, low, or unstable. Because the ECM controls everything, a bad power feed or ground can cause stalling, hard starting, or a no-start, and often triggers several unrelated codes at once. Start diagnosis at the battery, grounds, fuses, and the ECM power relay.
High
Can I keep driving? Risky — a faulty ECM power feed can cause stalling, hard starting, or a no-start, so diagnose it promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Intermittent stalling or the engine cutting out
- Hard starting or an intermittent no-start
- Multiple unrelated sensor codes stored at once
- Erratic gauges or electrical behavior
Common causes
Most likely first
- Corroded or loose ECM power connector or groundLikely
- Blown fuse or a failing ECM power relayCommon
- Weak battery, loose battery terminals, or a charging-system faultCommon
- Damaged power or ground wiring to the ECMLess often
- Faulty ECM (least common)Less often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data, then load-test the battery and check the terminals.
- Check the ECM fuses and swap-test or measure the ECM power relay.
- Inspect the ECM power and ground connectors for corrosion or looseness.
- Voltage-drop test the ECM power feeds and grounds while cranking and running.
- Repair the wiring or relay found at fault; replace the ECM only as a last resort.
FAQ
Quick answers
Is it safe to drive with P2505?+
Not really. An unstable power feed to the ECM can make the engine stall or refuse to start with little warning. Diagnose it before relying on the car.
Can I just clear P2505?+
Clearing it does not fix the power or ground problem, and it will return — often along with a stall or no-start. Repair the circuit first.
Related codes
Often seen with P2505
Read & clear P2505 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX