Powertrain, generic (extended)

P2AD1 Throttle/Pedal Position Sensor/Switch C/G Voltage Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2AD1 compares the voltages of position signals C and G and sets when they stop describing the same position. What the letters mean depends on the layout; GM's 2023 table 23OBDG07 for an engine with two throttle bodies is the clearest public key: C is sensor 1 and G sensor 2 of the bank 2 throttle (P0227/P0228 and P212C/P212D), so C/G is the internal pair of that second throttle, the counterpart of the bank 1 pair A/B under P2135. GM's table itself checks each track against modelled air charge rather than listing P2AD1, and no maker documents the code publicly. Typical causes are a worn track in the bank 2 throttle, contact resistance in its connector or a shared ground or reference fault. The ECU then usually limits throttle opening.

Likely causes

Raised contact resistance in the throttle connector
Worn or drifting sensor track in the second throttle body
Fault on the shared 5 V reference or sensor ground

Symptoms

  • Check engine light on
  • Reduced power or limited throttle response

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–3 h

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

Parts involved

throttle position sensor cthrottle position sensor gecm

Related codes

P2AD2P2AD3P2135P0228P212CP212D

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