P2511
ECM/PCM Power Relay Sense Circuit Intermittent
The sense (feedback) line that lets the ECM verify the main power relay has actually closed shows intermittent dropouts. The ECM expects to see battery voltage on this line whenever the relay is energised — short losses suggest aged contacts, vibration or chafed wiring.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Aged main relay contactsCommon
- Chafed sense wire shorting intermittentlyPossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Main Relay
- Sense Wire
P2511 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.