P21DA code meaning
Cylinder 12 Injector B Circuit/Open
Powertrain system Generic code P21xx codes Check engine light
What P21DA means
P21DA closes the circuit/open series of the second injectors with cylinder 12. It requires a twelve-cylinder engine with two injectors per cylinder; no manufacturer documents this code publicly and no available source names such an engine using it. The fault type is the same as for its documented siblings: the control unit switches the injector and sees no current or an impedance far above normal. GM's LT5 injection module, for example, treats 200 kOhm or more as open and stores a Type A fault after 20 of 25 samples. CARB demands this kind of electrical monitoring for injectors. Directly after this code the series continues with the low and high faults P21DB and P21DC for cylinder 1; the A-side open code for cylinder 12 is P020C, the misfire code P0312.
P21DA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P21DA
- Check engine light on
- Misfire on cylinder 12 (P0312)
Common causes of P21DA
- Most likelySecond injector of cylinder 12 with open coil
- PossibleWire or terminal fault in the injector harness
- Less likelyOutput stage of the controlling 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 P21DA 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. |
| DA | The exact fault in that area. |
What to do next
- Note P21DA 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 P21DA
What does P21DA mean?
P21DA means "Cylinder 12 Injector B Circuit/Open". P21DA closes the circuit/open series of the second injectors with cylinder 12. It is a generic code, so it means the same on every make.
Is it safe to drive with P21DA?
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 P21DA fail an emissions test?
Yes, it can. P21DA 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 P21DA to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P21DA clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.