P0271: Cylinder 4 injector: high signal in circuit
The ECU sees a voltage that is too high in the cylinder 4 injector circuit. Usually a loose connector, a broken wire or the injector itself.
| Code | P0271 |
|---|---|
| System | Engine and transmission |
| Group | P02xx, Fuel and injectors |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0271 means
Each injector is an electric valve that opens to spray fuel into its cylinder, and the ECU monitors its circuit while driving it. On cylinder 4 it has measured a higher voltage than expected, which nearly always means an open circuit: a broken wire, a loose plug or a burnt out injector coil. How the cylinders are numbered is set by each manufacturer.
Most common causes
- Injector connector unplugged, loose or corroded
- Injector wire broken by chafing or engine heat
- Injector coil open internally
- Control wire touching another live wire
- ECU fault in the injector driver, which is rare
Symptoms
- Engine warning light on
- Engine shakes or runs roughly, especially at idle
- Loss of power
- A misfire code for the same cylinder (P304) may also appear
Can you drive with P0271?
With care You can get to a workshop, but if that cylinder is not getting fuel properly the engine will misfire and the catalytic converter can suffer. If the warning light flashes or the engine shakes badly, stop driving.
Open the bonnetthe in-depth explanation
How to check it
With the engine off, check that the cylinder 4 injector connector is fully pushed on and free of green corrosion. A workshop can measure that injector’s resistance with a multimeter and compare it with the others.
How to read and clear P0271 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0271 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P026D The fuel injection quantity is above normal
- P026E The intercooler coolant pump gives readings outside the normal range
- P026F The coolant thermostat gives readings outside the normal range
- P0270 Cylinder 4 injector: low signal in circuit
- P0272 Cylinder 4 contributes uneven power compared with the others
- P0273 The cylinder 5 injector gives a lower signal than normal
- P0274 The cylinder 5 injector gives a higher signal than normal
- P0275 Cylinder 5 contributes unevenly to engine power
- P0200 Injector circuit malfunction
- P0201 Injector circuit malfunction, cylinder 1
- P0202 Injector circuit malfunction, cylinder 2
- P0203 Injector circuit malfunction, cylinder 3
What does code P0271 mean?
Each injector is an electric valve that opens to spray fuel into its cylinder, and the ECU monitors its circuit while driving it. On cylinder 4 it has measured a higher voltage than expected, which nearly always means an open circuit: a broken wire, a loose plug or a burnt out injector coil. How the cylinders are numbered is set by each manufacturer.
Can you drive with P0271?
You can get to a workshop, but if that cylinder is not getting fuel properly the engine will misfire and the catalytic converter can suffer. If the warning light flashes or the engine shakes badly, stop driving.
How do you clear P0271?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0271 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
