Powertrain, generic · Transmission

P0736 Reverse Incorrect Ratio

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. Thresholds: Ford more than 30 rpm off for 1.8 s three times (diesel 2023: over 20 % for 12 s), GM's 2006 tables and the Allison 1000 converter slip of 200–230 rpm for 2.25 s after one trip, Saab's Aisin boxes over 20 % twelve times without MIL. P0736 concerns reverse. The check needs reversing under load, so short manoeuvres are often not enough; a 2006 GM table sets it after 2 s of slip above 100 rpm without the diagnostic gear step used for forward gears. Slipping or delayed engagement of reverse, especially uphill, is typical; a worn reverse clutch or low/reverse brake is the usual cause.

Likely causes

Fluid level or condition
Reverse clutch or low/reverse brake worn
Valve body, shift valve or gasket
Oil pump or pump cover

Symptoms

  • Delayed or slipping engagement of reverse
  • No reverse uphill or under load
  • Transmission warning, limp mode, check engine light depending on manufacturer

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–3,500
Time0–14 h

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

Parts involved

transmission clutchestransmission valve bodytransmission fluidtransmission control module

Related codes

P0730P0731P072BP0705P0721

References: saabwisonline.com, gsi.ext.gm.com, gsi.ext.gm.com, newtonnet.co.uk.