Powertrain, generic (extended)

P2846 Shift Fork B Position Sensor Incorrect Neutral Position Indicated

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2846 flags a mismatch between the neutral reading of the fork B position sensor and the gear state the transmission module expects. Either the sensor claims fork B rests in neutral while the shaft speeds prove its gear carries load, or it reports an engaged fork where the module has commanded neutral. No manufacturer publicly documents P2846. CARB 13 CCR 1968.2 requires transmission inputs to be checked for rationality, and GM's 2023 Corvette dual-clutch table shows one way to do it: an unloaded rod has to read within a tolerance band around the learned neutral or engaged point. GM books such deviations for its second rod under P2837, though. Likely triggers are lost learned positions, a loosened sensor target or a worn detent; a relearn comes first.

Likely causes

Learned neutral position of fork B missing after repair or module replacement
Magnet or target on the fork B rod loosened or shifted
Worn detent letting fork B settle off its neutral point

Symptoms

  • Gears served by fork B refused or skipped
  • Transmission warning with reduced performance
  • Gear indicator disagrees with the actual gear

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time0.5–8 h

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

Parts involved

shift fork position sensor bshift fork btcm

Related codes

P2845P2847P2848P2837P2851

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