P0813
Reverse Output Circuit
General electrical fault on the reverse-output circuit — the line that drives backup lights, reverse alarm or transfer-case reverse signal. With the output broken these consumers cannot be activated.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
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
Common causes
Ordered by how often each turns out to be the cause.
- Open or shorted output wireCommon
Parts involved
- Reverse Output Circuit
- Wiring Harness
P0813 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.