P0291 code meaning
Cylinder 11 Injector A Circuit Low
Powertrain system Generic code P02xx codes Check engine light
What P0291 means
P0291 means the control wire of the cylinder 11 injector – the side the engine module switches to ground – is shorted to ground. GM detects this with the driver off: on direct injection at 1 V or less, on port injection and Duramax diesels at 0.5 Ω or less to ground. Ford's 6.7 diesel has its driver chip report the short within 0.3 s. Most systems switch the warning light on in the first trip (some GM port-injection engines and Saab's 2.0 turbo after two) and shut the affected injector off, so the cylinder misfires. Ford gasoline engines report all injector circuit faults as P0201 ff instead. Cylinder 11 exists only on twelve-cylinder engines; no manufacturer document using this code was found – GM and Ford documents stop at cylinder 8 – so the description follows CARB and the codes for cylinders 1–8.
P0291 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0291
- Check engine light on
- Misfire and rough running, misfire code P0311
- Loss of power, rough idle
- Injector shut off, limp mode possible on diesels
Common causes of P0291
- Most likelyControl wire of the cylinder 11 injector chafed to ground in the harness
- PossibleInjector connector damp or corroded, leakage to ground
- PossibleInjector shorted to its housing internally
- Less likelyOpen control wire (on some GM port-injection drivers this also reads low; P020x sets too)
- Less likelyDriver stage in the engine module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector cylinder 11Injector wiringEngine control module
What each part of P0291 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 2 | Area: fuel and air metering (injector circuit). |
| 91 | The exact fault in that area. |
What to do next
- Note P0291 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 P0291
What does P0291 mean?
P0291 means "Cylinder 11 Injector A Circuit Low". P0291 means the control wire of the cylinder 11 injector – the side the engine module switches to ground – is shorted to ground. It is a generic code, so it means the same on every make.
Is it safe to drive with P0291?
Drive gently and only to a workshop. With P0291 the car can go into limp mode (reduced power) to protect itself.
Will P0291 fail an emissions test?
Yes, it can. P0291 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 P0291 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0291 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.