Powertrain, generic (extended)

P2AD2 Throttle/Pedal Position Sensor/Switch B/G Voltage Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2AD2 sets when signals B and G no longer agree in voltage. On engines with one throttle body per bank this is a cross-bank comparison: with GM's 2023 letter scheme, B is the second track of the bank 1 throttle and G the second track of the bank 2 throttle. Mercedes-Benz uses P2AD2 on its M177 twin-turbo V8 (AMG C63, E63, GLE63, GT63, also GLE/GLS 580 and Maybach GLS 600): the third version (August 2026) of bulletin LI07.10-P-080384 added P2AD200 to its list and traces it, together with P2135, P2136 and P2AD3, to high resistance in the pins of both throttle actuators, left and right; the fix is new silver- and gold-plated terminals and seals. Drivers notice the check engine light and possibly reduced power.

Likely causes

High resistance at the pins of the throttle actuator connectors
Drifting position track in one of the throttle bodies
Damaged wiring to one throttle actuator

Symptoms

  • Check engine light on
  • Possible loss of power
  • Further throttle codes such as P2135 or P2136 stored

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–900
Time1–4 h

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

Parts involved

throttle position sensor bthrottle position sensor gecm

Related codes

P2AD1P2AD3P2135P2136P212B

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