Powertrain, generic (extended)

P21E7 Cylinder 6 Injector B Circuit High

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P21E7 is stored when the B injector of cylinder 6 shows a short toward power. GM's 2019 Corvette ZR1 with the LT5 V8 is the documented user; there the FICM checks the low side only in the driver-off state, flags 0.5 Ohm or less to power, and needs at least 11 V at the powertrain relay with the engine running. The result is a Type A fault after one trip. With the low side tied to supply, every switching attempt would push current straight into the driver, so the injector on the right-bank cylinder 6 delivers nothing. A useful check is to unplug the injector: if the voltage on the control wire stays, the harness is at fault; if it disappears, the injector coil is suspect. P21E6 is the matching low fault and P0277 the A injector high code.

Likely causes

Cylinder 6 B injector control wire in contact with a live wire

Shorted turns in the injector coil

Output stage of the injection control module damaged by the short

Symptoms

Check engine light on
Lean condition on bank 2 under load
Cylinder 6 misfire at high load

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–900

Time1–4 h

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

Parts involved

fuel injectorinjector wiringengine control module

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