P0801: Reverse Inhibit Control Circuit/Open

What it means

The TCM detects an electrical fault in the reverse inhibit solenoid circuit, which prevents engagement of reverse at high vehicle speeds.

At a glance

• Usually lights the check-engine light

How it works

The reverse inhibit solenoid is part of the transmission control that prevents reverse from engaging at high road speeds. The TCM monitors the solenoid’s electrical circuit and sets P0801 when it detects an open or other circuit fault.

Common causes

Most likely first.

1. Solenoid failed
2. Wiring or connector fault

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

How to diagnose it

1. Scan all modules and save freeze-frame data and transmission codes to see when the reverse inhibit fault occurred.
2. Check whether reverse-inhibit status or solenoid command data is available, and compare it with vehicle speed and the reported symptoms.
3. Inspect the reverse inhibit solenoid connector and its wiring for loose pins, corrosion, damage, or chafing.
4. Test the solenoid circuit for continuity and shorts, following the wiring diagram and the manufacturer’s specification.
5. If the wiring and solenoid pass, check the TCM connector and control circuit for a fault.

Common fixes

• Clean and secure the reverse inhibit solenoid connector.
• Repair damaged or open wiring in the solenoid circuit.
• Replace the failed reverse inhibit solenoid.
• Repair a confirmed TCM circuit fault.

Can I keep driving?

Avoid shifting into reverse while the vehicle is moving, and limit driving if shifts are harsh, slipping, or delayed. Continued transmission trouble can worsen shifting or leave the vehicle unable to select gears.