P0641
PowertrainPcm Referencemoderate severitySensor Reference Voltage A Circuit/Open
What P0641 Means
The PCM detected a problem with the 5-volt reference supply on circuit A. Multiple sensors sharing this reference may read incorrectly.
Symptoms
- Multiple sensor codes
- Check engine light on
- Erratic sensor readings
Common Causes
- Shorted sensor on reference circuit
- Damaged reference wiring
- Corroded connector
- Faulty PCM
Diagnostic Steps
- Scan for multiple sensor codes
- Measure 5V reference at affected sensors
- Disconnect sensors to isolate short
- Repair wiring or replace PCM
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