P21D0 code meaning
Cylinder 2 Injector B Circuit/Open
Powertrain system Generic code P21xx codes Check engine light
What P21D0 means
P21D0 is the open-circuit code for the B injector of cylinder 2. Where that cylinder sits varies: GM's small-block V8 alternates odd and even numbers between the banks, so cylinder 2 opens the right bank, while Ford's V6 and V8 count one bank first and place it next to cylinder 1. Ford defines B as the port injector, the direct injector being A with P0202. Ford runs the check in every engine with combined port and direct injection, from the three-cylinder 1.5 to the 5.0 V8, continuously at 11 V or more for 5 s. GM's LT5 injection module samples the circuit every 100 ms once the powertrain relay supplies at least 11 V. On engines that run on port fuel alone at light load, like Ford's second 3.5 EcoBoost, the cylinder then misfires mostly at idle. Low and high faults are P21DE and P21DF.
P21D0 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P21D0
- Check engine light on
- Misfire on cylinder 2, mainly at idle and light load
- Code P0302 stored as well
Common causes of P21D0
- Most likelyPort injector of cylinder 2 with an open winding
- PossibleBroken wire or pushed-back terminal in the injector harness
- 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 P21D0 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. |
| D0 | The exact fault in that area. |
What to do next
- Note P21D0 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 P21D0
What does P21D0 mean?
P21D0 means "Cylinder 2 Injector B Circuit/Open". P21D0 is the open-circuit code for the B injector of cylinder 2. It is a generic code, so it means the same on every make.
Is it safe to drive with P21D0?
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 P21D0 fail an emissions test?
Yes, it can. P21D0 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 P21D0 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P21D0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.