P21D3 code meaning
Cylinder 5 Injector B Circuit/Open
Powertrain system Generic code P21xx codes Check engine light
What P21D3 means
P21D3 can only appear on engines with at least five cylinders and two injectors per cylinder. Documented users are Ford's dual-injection V6 and V8 engines (2.7 and 3.5 EcoBoost of the second generation, 5.0 V8 from 2018) and GM's supercharged LT5 V8. Ford defines B as the port injector; the direct injector of this cylinder is A, coded P0205. GM stores it as Type A once 20 of 25 samples fail. Ford's check is continuous above 11 V with a 5 s window. GM's LT5 injection module rates an open by the impedance seen with the driver off, 200 kOhm or more. On a V6 one bank then runs with a single weak cylinder, which fuel trims and misfire counters can reveal.
P21D3 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 3.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P21D3
- Check engine light on
- Misfire on cylinder 5 (P0305)
- Fuel trim of one bank shifted
Common causes of P21D3
- Most likelyOpen coil in the cylinder 5 port injector
- PossibleBroken wire in the bank harness of the port injectors
- Less likelyOutput stage in the engine or injection module failed
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 P21D3 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. |
| D3 | The exact fault in that area. |
What to do next
- Note P21D3 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 P21D3
What does P21D3 mean?
P21D3 means "Cylinder 5 Injector B Circuit/Open". P21D3 can only appear on engines with at least five cylinders and two injectors per cylinder. It is a generic code, so it means the same on every make.
Is it safe to drive with P21D3?
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 P21D3 fail an emissions test?
Yes, it can. P21D3 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 P21D3 to fix?
Difficulty: medium. A typical repair takes 1 to 3.5 hours of work. This is a job for a workshop.
Will P21D3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.