Powertrain, generic (extended)

P2E12 Gear Selection Actuator Position Sensor Circuit Low

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P2E12 sets when the signal of the gear selection actuator's position sensor stays below the lowest valid level. Usual reasons are a short to ground on the signal line, a missing 5 V reference or a defect inside the sensor; with many designs an interrupted signal wire also reads low. No manufacturer documents P2E12 publicly. For a comparable digital rod position sensor, GM's 2023 dual-clutch TCM tables (P2833) give concrete limits: no pulses while the pin sits below 2000 mV, or a duty cycle under 8 %, confirmed after 150 ms with a supply between 4.5 and 5.5 V, Type A. CARB calls for out-of-range checks on such transmission inputs. If several sensors share the reference, other codes often appear at once. The high counterpart is P2E13; the gearbox usually falls back to a safe gear.

Likely causes

Signal wire chafed through and shorted to ground

5 V reference missing or pulled down by another sensor on the same supply

Signal wire or terminal interrupted

Internal short in the position sensor

Symptoms

MIL and transmission warning immediately
Limp mode, no gear changes or only one gear
Further sensor codes if the shared 5 V supply is affected

Repair estimate

DifficultyHardWorkshop job

Parts and labour€80–1,500

Time0.5–4 h

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

Parts involved

gear selection actuator position sensorwiring harnesstcm

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