P21D5 code meaning
Cylinder 7 Injector B Circuit/Open
Powertrain system Generic code P21xx codes Check engine light
What P21D5 means
P21D5 belongs to V8 engines with a second injector per cylinder. Two are documented: Ford's 5.0 V8, which gained direct injection alongside its port injectors in 2018, and GM's 2019 LT5, the supercharged Corvette ZR1 engine with primary direct and supplemental port injection. Ford's summary lists P21CF to P21D6 as port injector circuits, continuous above 11 V, 5 s. On the LT5 the B injectors hang on a separate injection module whose low-side driver flags an open at 200 kOhm or more with the output off, in 20 of 25 samples at 100 ms, Type A with MIL in one trip. Ford counts its V8 one bank after the other, so cylinder 7 lies on the second bank; GM alternates banks, making 7 the last cylinder on the left. The A-side code for cylinder 7 is P0207, the misfire code P0307.
P21D5 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P21D5
- Check engine light on
- Misfire on cylinder 7, on the LT5 mostly under high load
- Reduced power at full throttle
Common causes of P21D5
- Most likelyOpen winding in the cylinder 7 port injector
- PossibleBroken wire or terminal in the port injector harness of that bank
- Less likelySeparate fuel injection control module faulty (GM LT5)
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 P21D5 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. |
| D5 | The exact fault in that area. |
What to do next
- Note P21D5 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 P21D5
What does P21D5 mean?
P21D5 means "Cylinder 7 Injector B Circuit/Open". P21D5 belongs to V8 engines with a second injector per cylinder. It is a generic code, so it means the same on every make.
Is it safe to drive with P21D5?
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 P21D5 fail an emissions test?
Yes, it can. P21D5 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 P21D5 to fix?
Difficulty: medium. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P21D5 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.