P0813: Reverse Output Circuit
What to do
Check whether your reversing lights still work; if they do not, this fault is the reason and it is worth fixing promptly, since reversing at night without them is genuinely hazardous. The camera and parking sensors may also stop appearing.
What this code means
A fault in the module's output announcing that reverse is engaged, as distinct from the input telling it so. The two sit either side of the module and fail differently: the input problem means the module does not know, the output problem means it knows and cannot tell anything else.
In practice the output drives the reversing lamps and wakes the camera and parking aids, so the symptom is similar and the repair location is not. Reversing lamps that have stopped working are the giveaway, and they are also a roadworthiness matter in most places — a vehicle reversing at night with no white lamps is not visible as reversing.
Likely causes
Start here
- Open circuit in lamp wiring · moderate
- Failed reversing lamp bulbs · easy
Less common
- Wiring shorted to ground · moderate
- 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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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