OBD-II code · Powertrain (generic, extended)
P2509 ECM/PCM Power Input Signal Intermittent
The ECU detects sporadic interruptions of its supply voltage. The fault is set when supply drops below a threshold for short periods, often during cranking or due to a poor connection.
Is it safe to drive with P2509?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyPoor battery cable connection
- PossibleIntermittent main relay
- Less likelyConnector with intermittent contact under vibration
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Ecu Power Supply, Main Relay, Battery Terminals
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.