P2151 Fuel Injector Group B Supply Voltage High — Causes & Fix
Updated for 2026 diagnostics & repair guidance
P2151 at a Glance
What it means
The shared supply feeding injector group B has a voltage fault — reading high.
Most common cause
Harness damage on the shared feed, a shorted injector pulling the group down, or an ECU driver-stage fault.
Severity
Serious — several cylinders can cut out together.
Can you drive?
Not recommended. Multiple dead cylinders cause severe power loss.
Typical repair cost
£40-£120 for harness repair; £100-£350 per injector if one has shorted.
What Does P2151 Mean?
P2151 refers to the shared voltage supply for one bank ('group B') of injectors rather than a single cylinder. Because the feed is common, one shorted injector or one chafed harness section can disturb every injector in the group, which is why these codes often appear together with several cylinder-specific circuit codes.
Common Causes
Injector-Related Causes
Shorted injector coil dragging the group supply
A single failed injector with an internal short pulls the shared rail voltage out of range for the whole group.
Other Possible Causes
Damaged group supply wiring
The common feed wire chafes on the engine or corrodes at a bulkhead connector.
ECU driver-stage fault
The boost-voltage stage that fires this injector group has failed inside the ECU.
Symptoms Drivers Notice
- Sudden severe power loss
- Engine running on half its cylinders or stalling
- Multiple injector fault codes stored together
- Engine may crank but not start
Vehicles Commonly Affected
Can You Still Drive with P2151?
Avoid driving. With a whole injector group affected the engine may stall or refuse to restart, and continued cranking floods the exhaust with unburned fuel.
How Mechanics Diagnose P2151
- 1
Identify the injector group
Use the wiring diagram to establish which injectors share the affected supply.
- 2
Measure each injector coil
A shorted coil in the group condemns that injector.
- 3
Inspect the shared feed harness
Check the common supply wiring and connectors end to end.
- 4
Verify the ECU driver stage
Test the ECU output last, only after injectors and loom test clean.
Repair Solutions & Costs
Replace any shorted injector
Fit a tested remanufactured unit and code it to the ECU.
Repair the shared supply harness
Repair the damaged section of the common feed.
Repair or replace the ECU
Only when injectors and wiring are proven good.
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
Any injector whose coil measures shorted must be replaced — a short re-appears instantly and can damage the ECU driver stage if left in place.
Compatible Remanufactured Injectors
OEM bench-tested injectors for engines affected by P2151 — 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
View injector
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 P2151.
Cross Reference Numbers
OEM and alternative part numbers for injectors affected by P2151.
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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