Powertrain, generic · Transmission

P0813 Reverse Output Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P0813 concerns a signal 'reverse active' that a module puts out – usually the transmission module, on manual cars the engine or body module – for example to the back-up lamp relay, the reversing camera or the body module. Like other driver outputs it is checked by comparing commanded and actual state, which reveals an open circuit or a short. Saab's 2012 transmission module reports a short to positive on its park/neutral output in the same way. No manufacturer document with thresholds for the reverse output is available to us. Back-up lamps, camera or mirror tilt may stop working; driving itself is not affected, and CARB allows such outputs without the MIL.

Likely causes

Wire from module to relay or body module open or shorted
Back-up lamp relay or connected load faulty
Connector corroded
Module output stage faulty

Symptoms

  • Back-up lamps not working
  • Reversing camera or parking beeper does not activate
  • Stored code without driving effects

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reverse output circuitbackup lamp relaytransmission control module

Related codes

P0812P0801P0817P0705

References: law.cornell.edu, saabwisonline.com.