Powertrain, generic (extended)

P23F0 Camshaft B Position Signal Output Circuit Low (Bank 2)

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P23F0 is stored when the bank 2 camshaft B output stays at ground potential while the ECM expects it to float high. A low reading can come from insulation damage near the exhaust side, where heat makes harness sleeves brittle, or from a receiving module whose input has failed shorted. Following GM's published logic for P2615, the module samples every 100 ms and sets the fault after 40 bad samples out of 50; an open beyond about 200 kOhm is caught by the same test. These values are borrowed, since no maker publishes P23F0. A dead output leaves the downstream unit without engine phase information, so it may fall back to substitute values, which drivers notice as harsher shifts or disabled features.

Likely causes

Heat-damaged insulation on the exhaust side grounding the wire
Receiving module input failed short to ground
Defective output stage in the ECM

Symptoms

  • Code stored, engine itself unaffected
  • Harsher shifts or delayed gear changes
  • Features such as start-stop disabled

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–3 h

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

Parts involved

engine control modulecam position signal b b2 outputwiring harness

Related codes

P23EFP23F1P23EDP23EAP2615

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