Powertrain, generic (extended)

P21F1 Cylinder 11 Injector B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P21F1 describes a cylinder 11 B injector circuit that sits too high, i.e. its switched side is shorted to supply. The code exists in SAE J2012 for completeness of the cylinder series, but no public manufacturer source uses it, and no twelve-cylinder engine with two injectors per cylinder could be documented. CARB still requires an emission-relevant output to be checked for circuit faults, while allowing makers to combine fault types; a system could therefore report this short under the open code P21D9 instead. Electrically, a short to power keeps the injector from opening and loads the driver each time it switches. GM's LT5 V8 shows typical criteria for the same fault type, 0.5 Ohm or less to power in the driver-off state, Type A. Low fault: P21F0; A injector high: P0292.

Likely causes

Control wire of the cylinder 11 B injector shorted to power
Injector coil shorted
Control module driver damaged

Symptoms

  • Check engine light on
  • Cylinder 11 lean or misfiring (P0311)

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,200
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

P21F0P21D9P0292P21EFP21F3P0311

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