Powertrain, generic (extended)

P21E8 Cylinder 7 Injector B Circuit Low

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P21E8 covers a low, ground-side fault on the cylinder 7 B injector. GM lists it for the 2019 Corvette ZR1, where the LT5 V8 carries a direct and a supplemental injector per cylinder and cylinder 7 is the rearmost cylinder of the left bank (bank 1). The supplemental injectors have their own control module, the FICM, and that module stores the code: below 0.5 Ohm between low side and ground while its driver is off, 20 failures in 25 samples, continuous monitoring, Type A with the MIL in the first trip. Since the limit is close to a dead short, a slowly corroding connector usually shows up as a misfire before it trips this code. Expect rich running on bank 1. The neighbours are P21E9 (high) and, for the A injector, P0279; an open circuit on other makes appears as P21D5.

Likely causes

Cylinder 7 B injector wire grounded at the rear of the engine

Injector coil leaking to ground

FICM output faulty

Symptoms

Check engine light on
Rich mixture reported for bank 1
Misfire on cylinder 7

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, lsxmag.com.