What does it mean?
P1667 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Reverse Inhibit Solenoid Control Circuit Malfunction .
Symptoms
- MIL on, often with a transmission warning lamp
- Reverse is blocked, delayed, or engages with a hard clunk
- The vehicle may creep in reverse or refuse to engage reverse at all
- Reverse lockout at road speed no longer works, so reverse can be selected when it should be inhibited
- Transmission drops into limp mode and other transmission codes appear
Likely causes
- Reverse inhibit solenoid coil open or shorted internally
- Transmission case connector contaminated with fluid, or corroded from road spray
- Harness chafed against the transmission case or heat damaged near the exhaust
- Open or shorted control wire between the solenoid and the control module
- Blown fuse on the solenoid supply feed
- Valve body contamination from old, burnt fluid keeping the solenoid from moving
- Failed output driver in the control module
How to fix it
- Check transmission fluid level and condition first; burnt fluid and debris cause solenoid faults
- Scan for companion transmission codes and read the commanded solenoid state on live data
- Inspect the transmission case connector for fluid wicking, corrosion and heat damage
- Measure the solenoid resistance at the case connector and compare it with specification
- Test the control wire back to the module for continuity and for shorts to ground and battery voltage
- Command the solenoid with the scan tool and listen or feel for it actuating
- Replace the solenoid or the affected valve body component if it is electrically bad, and consider the module last