Powertrain, generic (extended)

P2852 Shift Fork Position Sensor C/D Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2852 pairs the position sensors of forks C and D and sets when their readings do not fit together. In GM's numbering these are rods 3 and 4, both on the even shaft and fed from the second sensor reference; a reference fault there would shift both signals together. No published OBD summary actually uses P2852: GM keeps rods 3 and 4 apart with P283C and P2841, and Ford's TR9070 lists consistency faults for shift rod sensors 3 and 4 in the same two codes. CARB 13 CCR 1968.2 is therefore the only basis. Diagnosis starts with the two signals in live data while each fork is moved by a scan-tool test; if both deviate in the same direction, wiring or supply is more likely than the sensors themselves.

Likely causes

Reference voltage feeding the C and D sensors out of tolerance
Sensor C or D reporting a shifted value
Input circuit fault in the transmission module

Symptoms

  • Gears of forks C and D unavailable
  • Transmission fault message, reduced power

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time1–8 h

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

Parts involved

shift fork position sensor cshift fork position sensor dtcm

Related codes

P2851P283CP2841P2847P2848

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.