Powertrain
generic / SAE
P0646
A and C Clutch Relay Control Circuit Low
Same as P0645 with the control line shorted to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number6 / 46
Possible causes
- Control line shorted to ground high
- Connector pins corroded - high contact resistance low
- Harness chafing through insulation low
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 60–250 €
- Estimated time: 0.3–1.2 h
- Component: ac clutch relay
- MIL / check engine light
Sources
References
sae:J2012