What Does P0813 Mean?
The Reverse Output Circuit has detected a fault. This circuit is the PCM's output that controls devices activated when reverse gear is engaged, such as the reverse lights relay, parking sensor activation, or backup camera power. The PCM has detected that its output command is not being properly delivered or the circuit feedback does not match the expected state.
Common Causes
30%
Blown reverse light fuse or failed relay
25%
Open or shorted wiring in the reverse output circuit
20%
Burned out reverse light bulbs causing open circuit detection
15%
PCM internal output driver failure
10%
Corroded bulb sockets or ground connections
Diagnostic Steps
1
Check the reverse light fuse in the fuse box — a blown fuse is the simplest cause and should be checked first.
2
With transmission in reverse, check for voltage at the reverse light bulb sockets — no voltage points to a wiring or relay issue.
3
Test both reverse light bulbs and sockets — a high-resistance corroded socket can cause circuit feedback issues even if the bulbs appear to work dimly.
4
If a reverse relay is used, test relay operation by swapping with an identical relay from another circuit or testing it on the bench.
5
Check the PCM output by backprobing the reverse output pin at the PCM connector while shifting into reverse — verify the PCM is commanding the output.
Estimated Repair Cost
$10 - $250
Parts + labor, varies by vehicle and location
The Reverse Output Circuit has detected a fault. This circuit is the PCM's output that controls devices activated when reverse gear is engaged, such as the reverse lights relay, parking sensor activation, or backup camera power. The PCM has detected that its output command is not being properly deli...
The most common cause of P0813 (Reverse Output Circuit) is: Blown reverse light fuse or failed relay
Typical repair costs for P0813 range from $10 to $250, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Reverse lights may not function, creating a significant safety hazard when backing up, especially in low visibility conditions. Backup cameras and parking sensors may also be inoperative. Repair as soon as possible.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0813 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control / Lighting System
Difficulty
Type
Generic (SAE)
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