P2509
- Powertrain
- Manufacturer-specific
Diagnose soon
Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
ECM/PCM Power Input Signal Intermittent
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
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.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
- Urgency
- Diagnose soon
- Will it pass emissions
- Not affected
- Check engine light
- Solid
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Poor battery cable connection | Very common | — |
| 2 | Intermittent main relay | Common | — |
| 3 | Connector with intermittent contact under vibration | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Ecu Power Supply
- Main Relay
- Battery Terminals
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
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