P0801: Reverse Inhibit Control Circuit/Open
Standardized SAE J2012 code · P08xx — Transmission
What does P0801 mean?
On GM manual gearboxes (Tremec T56/TR6060 in Corvette, Camaro, CTS-V and ATS-V) the engine module drives a solenoid that blocks reverse while the car moves forward. P0801 means its control circuit is open. GM's tables describe the check: the low-side driver's internal diagnosis flags an open line with at least 9 V and the engine above 250 rpm, 20 failures in 25 samples of 250 ms – about 6 s; in 2006 a 5 s comparison of commanded and actual driver state. GM rates it type C, emissions-neutral and without MIL, from 2019 with a 'service vehicle soon' note. Depending on how it fails, reverse cannot be engaged or is no longer blocked. The title was updated to the current J2012 wording with '/Open'.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Reverse hard or impossible to engage
- Reverse no longer blocked
- Service note in the driver display, usually no MIL
Common causes
- High Connector at the reverse inhibit solenoid loose or corroded
- Medium Solenoid coil open
- Medium Harness between engine module and gearbox damaged
- Low Engine module driver faulty
Likelihood is a general estimate across vehicles; your make and model may differ.
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