Powertrain, generic (extended)

P21BE Cold Start Cylinder 9 Injection Timing

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

A ninth cylinder exists only on V10, V12 and W12 engines, so P21BE is limited to a handful of models. Petrol engines in this class with direct injection include the 5.2-litre V10 of Lamborghini and Audi (Huracán, R8, S6 and S8) and the 6.3-litre W12 FSI of the Audi A8, which feeds its injectors from two high-pressure pumps and two rails. Whether their engine modules use P21BE is not documented publicly, and no other manufacturer source names the code. Its meaning follows from the series: during the cold-start heating phase the injection timing of cylinder 9 deviated from its target, a fault CARB wants reported apart from warm-engine faults. There is no cold-start injection pulse code beyond cylinder 8. Related: P021C (warm), P0209, P0309.

Likely causes

Direct injector of cylinder 9 with deposits or slow response
Wiring or connector fault at injector 9
Low pressure on the rail feeding cylinder 9 (engines with two rails)

Symptoms

  • Check engine light after cold starts
  • Slightly uneven idle while the engine is cold

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€200–2,500
Time1.5–7 h

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

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P21BDP21BFP021CP0209P0309P05EC

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