P0274 Injector Circuit High (Cylinder 5) — Causes & Fix
Updated for 2026 diagnostics & repair guidance
P0274 at a Glance
What it means
The ECU has measured a voltage above the expected range in the cylinder 5 injector circuit.
Most common cause
Injector solenoid resistance out of specification, wiring short, or connector corrosion.
Severity
Moderate to serious — the ECU may cut fuel to cylinder 5, causing a misfire.
Can you drive?
Short distances only. Prolonged driving risks DPF and catalytic converter damage.
Typical repair cost
£100-£350 for injector replacement; £40-£100 for wiring repair.
What Does P0274 Mean?
P0274 is a generic OBD-II code meaning the Engine Control Unit measured a signal voltage above the expected window in the fuel injector circuit for cylinder 5. A 'high' circuit reading usually points to a break in the circuit, a short to battery voltage, or an injector coil with too much resistance. The ECU will often disable fuel delivery to cylinder 5 to protect the driver stage, so the engine runs with a dead cylinder until the fault is repaired.
Common Causes
Injector-Related Causes
Injector solenoid resistance out of specification
The injector coil has degraded with heat and age so its resistance no longer matches the ECU's expected window. Most common on engines over 80,000 miles.
Other Possible Causes
Wiring short or break to cylinder 5 injector
A chafed or corroded harness section between the ECU and cylinder 5 injector pulls the measured voltage high.
Corroded injector connector
Water ingress at the injector plug creates resistance that skews the circuit reading.
ECU injector driver fault
The output transistor driving this injector has failed. Less common — verify the injector and loom first.
Symptoms Drivers Notice
- Misfire from cylinder 5, most obvious at idle
- Engine management light on
- Loss of power and rough running
- Increased fuel consumption
Vehicles Commonly Affected
Can You Still Drive with P0274?
Driving short distances is usually possible but the engine will misfire and unburned fuel can damage the DPF and catalyst. Have the circuit tested promptly.
How Mechanics Diagnose P0274
- 1
Read freeze-frame data
Confirm which cylinder logged the fault and the conditions stored with it.
- 2
Measure injector coil resistance
Test at the cylinder 5 injector plug and compare the reading with specification.
- 3
Inspect the harness and connector
Wiggle-test the loom section and connector for chafing or corrosion.
- 4
Swap-test the injector
Move the injector to a neighbouring cylinder — if the code follows the injector, the injector is at fault.
- 5
Verify the ECU driver output
Check the ECU output stage only after the injector and loom test clean.
Repair Solutions & Costs
Repair the wiring or connector
Repair or replace the damaged harness section or corroded connector.
Replace the cylinder 5 injector
Fit a tested remanufactured unit if the coil is out of specification.
Code the replacement injector
Write the injector calibration code to the ECU following the manufacturer procedure.
Replacing injectors? Browse our remanufactured diesel injectors, reconditioned injectors or refurbished diesel injectors — all bench-tested with a 12-month warranty.
When Injector Replacement Is Required
If the injector coil resistance is out of specification or the fault follows the injector in a swap test, the injector must be replaced — coil failure cannot be repaired in situ.
Compatible Remanufactured Injectors
OEM bench-tested injectors for engines affected by P0274 — verified pricing, 12-month warranty, free UK delivery.
Delphi A6510704987
Remanufactured Delphi 28272472DNR diesel injector for Mercedes-Benz 2.1 CDI OM651 engines. Direct-fit replacement for C-Class, E-Class, CLA, GLA, GLK, Vito, V-Class, Sprinter and SLK applications. Cross-references A6510704987, A6510702387, HRD351, 28272472. OEM-tested and calibrated with full flow and leak-back verification. Includes 12-month unlimited-mileage warranty. Supplied as an exchange unit — return your old injector within 30 days.
Fits: OM651, OM651.911, OM651.924, OM651.925
View injector
Bosch 0445110613
BMW 2.0d B47 Remanufactured Common Rail Injector
Fits: B47, B47C20A, B47D20, B47D20A
View injector
Bosch 13538514148
2.0L Diesel Remanufactured Solenoid Injector (BMW B47)
Fits: B47, B47C20A, B47D20, B47D20A
View injector
Delphi 28307309
Delphi remanufactured diesel injector for Mercedes OM651 applications. OEM tested and calibrated on CR318 PRO test bench. 12-month warranty included. Free UK delivery. Suitable for professional garage use. Exchange unit — return your old injector within 30 days.
Fits: OM651.955, OM651.956, OM651.957, OM651.958
View injector
Delphi 28388960
Remanufactured Delphi 28388960 diesel injector for Ford 2.0 TDCi and Peugeot/Citroen 2.0 HDi/BlueHDi DW10 engines. Direct replacement for Ford Mondeo, Kuga, S-Max, Galaxy, Focus, C-Max, Edge and Peugeot 308, 508, 3008, 5008, Expert, Citroen C4, C5, DS4, DS5, Jumpy, Jumper applications. Cross-references 28602948, 9674984080, DS7Q9F593BA, HRD360. OEM-tested and calibrated with full flow and leak-back verification. Includes 12-month unlimited-mileage warranty. Supplied as an exchange unit — return your old injector within 30 days.
Fits: DW10C, DW10CB, DW10CT, DW10CTED4
View injector
Bosch 0445110601
BMW 2.0d N47 Remanufactured Common Rail Injector
Fits: N47C20A, N47D20A, N47D20C
View injector
Bosch 0445110616
BMW 2.0L / 3.0L Diesel Remanufactured Common-Rail Injector (N47/N57)
Fits: N47D20B, N47D20C, N47D20O1
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Siemens VDO / Continental 5WS40156Z
DW10 / 2.0 HDi / 2.0 TDCi / D4204T Remanufactured Common Rail Injector
Fits: DW10CB, DW10CTED4
View injectorCompatible Injector Part Numbers
6 injectors compatible with engines affected by P0274.
Cross Reference Numbers
OEM and alternative part numbers for injectors affected by P0274.
Affected Vehicle & Engine Combinations
Need a Replacement Injector?
UK-tested remanufactured injectors with 12-month warranty. Search by engine code or vehicle registration.
Need it fast? Same-day dispatch on in-stock injectors.
Order before 2pm for next working day delivery (UK mainland). Call us on 020 3355 6581.
Engine-Specific Guides
Frequently Asked Questions
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Fault Codes
Why It Happens
Common-rail injectors live at extreme pressures with clearances measured in microns. Fuel quality, heat cycles and mileage wear the internal control valve and nozzle: back-leak rises, spray patterns deteriorate and delivery drifts from calibration. Most 'engine' complaints on high-mileage diesels trace back to this gradual injector wear.
Professional Diagnosis
Workshops follow a fixed order: scan for codes and freeze-frame data, compare requested vs actual rail pressure on live data, read cylinder balance corrections, then run a comparative leak-off test. That sequence identifies the faulty injector without guesswork — and prevents needlessly replacing pumps, sensors or the wrong injector.
Typical Workshop Findings
The most frequent findings are: one injector returning several times the leak-off volume of its neighbours; carbon build-up from a failed copper washer; corroded injector connectors; and missing injector coding after a previous repair. Genuine high-pressure pump failures are rarer than back-leak faults that mimic them.
When to Replace Injectors
Replace when testing proves internal wear: leak-off clearly above the other injectors, balance corrections at their limits, or a failed bench test. Cleaning and additives cannot restore worn internal clearances. Bench-tested remanufactured injectors restore original calibration at a fraction of the new price — always coded to the ECU where the engine requires it.
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