Powertrain, generic (extended)

P21DA Cylinder 12 Injector B Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P21DA closes the circuit/open series of the second injectors with cylinder 12. It requires a twelve-cylinder engine with two injectors per cylinder; no manufacturer documents this code publicly and no available source names such an engine using it. The fault type is the same as for its documented siblings: the control unit switches the injector and sees no current or an impedance far above normal. GM's LT5 injection module, for example, treats 200 kOhm or more as open and stores a Type A fault after 20 of 25 samples. CARB demands this kind of electrical monitoring for injectors. Directly after this code the series continues with the low and high faults P21DB and P21DC for cylinder 1; the A-side open code for cylinder 12 is P020C, the misfire code P0312.

Likely causes

Second injector of cylinder 12 with open coil
Wire or terminal fault in the injector harness
Output stage of the controlling module failed

Symptoms

  • Check engine light on
  • Misfire on cylinder 12 (P0312)

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

P020CP21F2P21F3P21D9P21DBP0312

References: law.cornell.edu, gsi.ext.gm.com.