Powertrain, generic · Transmission

P08A4 Gear Lever X Position Sensor 1/2 Correlation

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

An electronic selector lever with redundant sensing measures the X axis with two sensors. P08A4 means the two X readings no longer agree although each may be within its own limits. No manufacturer documents P08A4 publicly. GM, which runs dual PWM lever sensors, folds this comparison into the range/performance codes: P089B sets when X sensor 2 differs from sensor 1 by more than 12 % duty cycle. GM patents describe the principle: each sensor is checked against the gate and against its partner, and on disagreement the module trusts the more robust signal or commands neutral or park. CARB 1968.2 (e)(15) demands such plausibility monitoring. Y-axis counterpart is P08A5, the whole system P08A6.

Likely causes

One of the two X sensors drifting
Magnet carrier or lever mechanism shifted or worn
Contact resistance on one sensor's signal path

Symptoms

  • Shifter warning message
  • Range selection refused or vehicle held in neutral or park
  • Check engine light, depending on the manufacturer

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–1,000
Time0.5–2.5 h

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

Parts involved

gear lever x position sensor 1gear lever x position sensor 2tcm

Related codes

P08A5P08A6P082AP089BP0821

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