Powertrain, generic (extended)

P2866 Shift Fork E Position Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2866 is the high-level fault of the fork E sensor input. GM's Corvette TCM, reading rod 5 as a pulse-width signal, stores it as Type A in two situations: the line delivers no pulses and stays above 3500 mV, or the duty cycle climbs past 92 %. Either must persist for 150 ms, and the check pauses during cranking or when battery or reference voltage lies outside its window. On the Mercedes 8G-DCT the matching entry P286600 is described as a short to positive of the fork E sensor. Possible reasons are a signal lead touching a supply wire, an open ground of the sensor that lets the line float up, or a sensor that latches its output. P2865 is the low counterpart; a signal that pulses at the wrong rate sets P2867 instead.

Likely causes

Fork E signal wire touching a supply voltage wire
Open ground of the fork E sensor letting the signal float high
Sensor electronics holding the output permanently high

Symptoms

  • Gears of fork E withheld, warning shown
  • Engine lamp after a short drive

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time0.5–8 h

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

Parts involved

shift fork eshift fork position sensor ewiring harness

Related codes

P2865P2863P2867P2864P2843

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.