Powertrain, generic (extended)

P21C0 Cold Start Cylinder 11 Injection Timing

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P21C0 applies only to twelve-cylinder engines (V12 or W12), since passenger-car engines with exactly eleven cylinders do not exist. Examples with direct injection are BMW's N74 twin-turbo V12, found in the BMW 760i and in Rolls-Royce models such as Ghost, Wraith and Dawn, and the 6.3-litre W12 FSI. The code would report that cylinder 11 missed its cold-start injection timing, for instance when the extra injection for catalyst heating is shifted. Whether BMW, Rolls-Royce or Audi use P21C0 is not documented publicly. The legal basis is CARB's demand for separate cold-start diagnostics, allowing the module to tell such faults apart from warm-running timing faults (P021E). Related: P0211 (injector circuit), P0311 (misfire).

Likely causes

Direct injector of cylinder 11 with changed opening behaviour
Heat-damaged wiring or connector at injector 11
Injector driver for cylinder 11 in the engine control module faulty

Symptoms

  • Check engine light after cold starts
  • Barely noticeable on the road; a twelve-cylinder engine masks a single cylinder well

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€250–3,000
Time2–8 h

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

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P21BFP21C1P021EP0211P0311P05EC

References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org.