P21E8 code meaning
Cylinder 7 Injector B Circuit Low
Powertrain system Generic code P21xx codes Check engine light
What P21E8 means
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.
P21E8 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P21E8
- Check engine light on
- Rich mixture reported for bank 1
- Misfire on cylinder 7
Common causes of P21E8
- Most likelyCylinder 7 B injector wire grounded at the rear of the engine
- PossibleInjector coil leaking to ground
- Less likelyFICM output faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injectorInjector wiringEngine control module
What each part of P21E8 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| E8 | The exact fault in that area. |
What to do next
- Note P21E8 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P21E8
What does P21E8 mean?
P21E8 means "Cylinder 7 Injector B Circuit Low". P21E8 covers a low, ground-side fault on the cylinder 7 B injector. It is a generic code, so it means the same on every make.
Is it safe to drive with P21E8?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P21E8 fail an emissions test?
Yes, it can. P21E8 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P21E8 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P21E8 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.