Damaged wiring to the cylinder 5 injector, such as chafing or a short to a voltage supply; Faulty cylinder 5 injector with an internal electrical fault; Corroded, loose or contaminated injector connector or ECU connector terminals; Poor earth or a power supply problem affecting the injector circuit; Fault in the injector driver inside the engine control unit; Wiring harness fault from previous engine work or heat damage near the cylinder 5 area.

P0274

Cylinder 5 Injector A Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
74: FaultThe specific fault in that area

What it means

P0274 means the engine control unit has detected a high electrical signal on the cylinder 5 injector circuit. The ECU monitors the injector driver and its feed or control wire, and it set the code because the voltage or current was higher than expected, which often points to a short to voltage or an internal fault in the injector or driver. The exact circuit layout and the meaning of 'A' varies by engine, so check model-specific information.

Symptoms

Engine misfire or rough running, particularly on cylinder 5
Malfunction indicator lamp on
Reduced power or the car going into limp mode
Hesitation or poor idle
Hard starting or a no-start
Increased fuel consumption or a fuel smell

Possible causes

Damaged wiring to the cylinder 5 injector, such as chafing or a short to a voltage supplylikely
Faulty cylinder 5 injector with an internal electrical faultlikely
Corroded, loose or contaminated injector connector or ECU connector terminalspossible
Poor earth or a power supply problem affecting the injector circuitpossible
Fault in the injector driver inside the engine control unitrare
Wiring harness fault from previous engine work or heat damage near the cylinder 5 areapossible

How to diagnose

Read all stored and pending codes and note any other injector or misfire codes, then review the freeze frame data for conditions when the fault set.
Visually inspect the cylinder 5 injector connector and harness for chafing, heat damage, oil contamination, bent pins or corrosion.
Check the injector and ECU connector terminals for tightness and good pin tension.
Measure the injector resistance and compare it with the manufacturer's specification for the engine.
With the connector unplugged and the ignition on, check the injector circuit wiring for an unwanted short to voltage and for continuity back to the ECU.
Check the relevant fuses, relay and power and earth supplies feeding the injector circuit.
Where the engine design allows, swap the cylinder 5 injector with another cylinder, clear the code and see whether the fault follows the injector.
If the wiring and injector prove sound, check for the manufacturer's ECU diagnostic information before suspecting the control unit.

How to fix

Repair or replace the damaged section of wiring and secure it away from heat and sharp edges.
Replace the faulty cylinder 5 injector, following the manufacturer's procedure and any coding or adaptation required for the engine.
Clean or replace corroded connectors and terminals.
Restore any faulty power or earth supply to the injector circuit.
Repair or replace the engine control unit only after the wiring and injector have been proven good.

Can I keep driving?

Medium severity

Short, careful driving to a workshop may be possible, but a high-circuit injector fault can cause misfires and unburnt fuel, so get it fixed soon. If the car runs very roughly, flashes the warning lamp or enters limp mode, stop driving and arrange recovery.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.