Powertrain, generic (extended)

P21D8 Cylinder 10 Injector B Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P21D8 covers the second injector of cylinder 10, the last cylinder of a V10. No manufacturer documents this code publicly. A V10 with two injectors per cylinder is on record in the Lamborghini Huracán, whose engine combines direct and multipoint injection, yet which of them its software would call B is unknown. For comparison, Ford's eight-cylinder logic tests B circuits continuously above 11 V for 5 s, and GM's LT5 module rates an open by 200 kOhm or more with the driver off. CARB obliges makers to monitor injector output circuits whose failure can raise emissions. In practice the fault would show as a misfire on cylinder 10 (P0310) with that cylinder still fed by its other injector; the A-side equivalent would be P020A. Neighbours are P21D7 and P21D9.

Likely causes

Second injector of cylinder 10 open internally
Wiring or connector fault at the cylinder 10 injector
Output stage in the engine control module failed

Symptoms

  • Check engine light on
  • Misfire on cylinder 10 (P0310)

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,000
Time1–5 h

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

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P020AP21EEP21EFP21D7P21D9P0310

References: law.cornell.edu, en.wikipedia.org, gsi.ext.gm.com.