Powertrain, generic · Transmission

P085D Gear Shift Control Module A Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Gear shift control modules A and B are selector modules of shift-by-wire systems, such as Audi's selector lever J587 or Stellantis' rotary shift module. The codes cover a dedicated link to the gearbox module and the module's plausibility. If the selected range cannot be transferred reliably, the gearbox holds its range, goes to P at standstill or into limp mode. Modules on CAN report lost communication as U0103 or invalid data as U0404 instead; GM uses its own codes. P085D means communication works, but the data or status of module A are implausible. Audi documents it on the 2019–21 A6/A7 family: the gearbox module stores P085D when the selector lever reports position sensor or P-button faults; drivers see a selector warning and cannot select a range. A software update of the lever fixes its over-sensitive voltage evaluation.

Likely causes

Selector module software (Audi update J587)
Selector module faulty: position sensor, P button
Supply voltage dips at the module
Connector or wiring at the lever

Symptoms

  • Selector lever fault shown in the cluster
  • No range selectable, car stays in P
  • Gearbox limp mode

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,200
Time0.3–2 h

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

Parts involved

electronic shift moduletransmission control moduleserial data linemodule wiring

Related codes

P085EP0860P0861P0862U0103U0404

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.