Powertrain, generic · Ignition system or misfire

P037C Cold Start Camshaft Profile System Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

To heat the catalyst quickly after a cold start, some engines select a particular camshaft profile; CARB counts altered valve timing among these cold-start measures and requires components of the cold-start strategy to have their own diagnostics. P037C checks whether the requested profile is actually engaged during this phase. It is documented by code only at GM, on the 2.7-litre turbo four-cylinder (L3B) with a three-step sliding camshaft: while catalyst heating is active, the measured lift state is compared with the cold-start target, and if it is wrong in 100 of 120 cylinder events the code is set in the first trip. Two GM bulletins (19-NA-145 for 2019 Silverado/Sierra 1500 with stalling on remote start below −6 °C, 20-NA-174 for the 2020 Cadillac CT4) trace P037C to a software fault and reprogram the engine module.

Likely causes

Engine module software (GM L3B, reprogramming)
Profile actuator (sliding cam pin) sticking or not switching
Actuator circuit (connector, wiring)
Wrong oil viscosity or low oil level, mechanism stiff when cold

Symptoms

  • Check engine light on
  • Rough running or stalling when cold (for example on remote start)
  • Often no noticeable symptoms

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,500
Time0.5–5 h

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

Parts involved

camshaft profile actuatorsliding camshaftengine control module

Related codes

P050AP050BP052AP054AP03EC

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