Powertrain, generic (extended)

P23EF Camshaft B Position Signal Output Circuit/Open (Bank 2)

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modePossible

P23EF covers the last combination of this series: camshaft B, usually the exhaust shaft, on bank 2, the cylinder bank without cylinder 1. On V-engines with four camshafts the ECM can provide a separate phase output per shaft, and P23EF says the bank 2 exhaust output has lost circuit continuity – a broken wire, a terminal backed out of its connector or a missing load at the receiving end. No manufacturer documents P23EF publicly. GM evaluates its comparable camshaft A outputs only with the engine not cranking and the powertrain relay at 11 V or more, and those faults do not turn on the MIL. Shorts are separated out as P23F0 (to ground) and P23F1 (to power); bank 1 has the same open-circuit check under P23EC.

Likely causes

Wire break in the bank 2 camshaft B output line

Terminal backed out of the connector housing

Receiving module disconnected or with failed input

Symptoms

Code stored without warning lamp on many vehicles
Module relying on the signal sets its own fault codes

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

P23F0 P23F1 P23EC P23E9 P2614 P0390

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