Powertrain, generic · Transmission

P07FF Cold Start Transmission Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P07FF means the transmission does not work as expected during the cold-start phase, shortly after starting with cold, thick fluid – for example a gear preselection or a clutch or valve response outside the expected window. The only documented user is Mercedes-Benz: its 2024 bulletin for the eight-speed dual-clutch gearbox 8G-DCT in the compact models (A-Class, CLA, GLA, GLB) names P07FF together with P0921, with reverse not available, a possible limp-home mode and the MIL; after switching off and on everything works again, and the fix was new control unit software. No thresholds or trip counts are published. It is not CARB's cold-start emission strategy, which concerns engine and catalyst heating (P050A ff), but a functional check of the transmission.

Likely causes

Transmission control module software misjudging the cold phase
Shift valve or hydraulics too slow with cold fluid
Wrong or aged fluid, low level
Fluid temperature sensor reading wrong

Symptoms

  • Reverse not available (message in the cluster)
  • Check engine lamp on
  • Limp-home mode shortly after a cold start
  • Normal again after switching off and on

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–300
Time0.5–2 h

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

Parts involved

transmission control moduletransmission mechatronicstransmission fluidtransmission fluid temperature sensor

Related codes

P0921P0700P0711P0712P0713

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