P0801: Reverse Inhibit Control Circuit/Open
What to do
If reverse will not engage at all, that is more likely to be this protective circuit stuck on than the gearbox having failed. Say so, and ask for the reverse inhibit circuit to be tested before any internal work is quoted — the two produce the same complaint and cost enormously different amounts.
What this code means
A fault in the circuit that prevents reverse being selected while the vehicle is moving forward. The inhibit exists because engaging reverse at speed would destroy the transmission in seconds, and it is one of the few protections whose value is obvious the moment it is explained.
The failure that matters is the inhibit staying engaged: reverse cannot be selected at all, at any speed, including stationary. To a driver that is indistinguishable from the gearbox having lost reverse, which is an alarming and expensive-sounding conclusion — when in fact the transmission is entirely healthy and a protective device has stuck on. Anyone facing a quote for internal transmission work on a no-reverse complaint should establish that this circuit was checked first.
Likely causes
Start here
- Faulty reverse inhibit solenoid · moderate
- Open circuit in solenoid wiring · moderate
Less common
- Corroded transmission connector · moderate
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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- The car — make, model, year and engine. The same fault behaves differently on each.
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