Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P050B Cold Start Ignition Timing Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

After a cold start the engine module raises idle speed and air mass and retards the ignition so that much heat goes into the exhaust and the catalyst lights off quickly. CARB requires this cold-start strategy to be monitored with its own codes, separate from ordinary idle and ignition faults. Ford collects data during the first 15 s after a cold start (coolant and catalyst 20–100 °F) and judges after 300 s, once per trip. P050B checks the ignition part of the strategy – the retard for catalyst heating; CARB allows checking only the commanded value. Ford sets it when desired and commanded cold-start timing differ by more than 10°, for example because knock, torque or idle control take back the retard. FCA fixed P050B on the 2.0-litre turbo Wrangler of 2018–19 with software. GM has no separate monitor.

Likely causes

Engine module software or calibration
Idle control takes back the retard because speed would drop (false air, dirty throttle)
Knock control or knock sensor intervenes
Extra load or alternator at cold start

Symptoms

  • Check engine light on
  • Usually no noticeable symptoms
  • Catalyst warms up more slowly after a cold start

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–250
Time0.5–1.5 h

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

Parts involved

ignition timing controlcold start strategyengine control module

Related codes

P050AP050EP0300P0325P0505

References: law.cornell.edu, newtonnet.co.uk, static.nhtsa.gov.