P2146 Injector Group A Supply Voltage — Causes & Fix
Updated for 2026 diagnostics & repair guidance
P2146 at a Glance
What it means
The ECU has detected a supply voltage fault affecting injector group A (typically cylinders 1 and 4).
Most common cause
ECU injector driver failure, main relay fault, or wiring short.
Severity
Serious — can affect two cylinders simultaneously.
Can you drive?
Not recommended. Two cylinders may be disabled.
Typical repair cost
£200-£500 for ECU repair; £100-£350 per injector if required.
What Does P2146 Mean?
P2146 is a manufacturer-specific code indicating the ECU has detected a voltage fault in the power supply to injector group A. On most diesel engines, injectors are grouped in pairs — group A typically covers cylinders 1 and 4. This code usually indicates an internal ECU fault rather than an injector problem, but injector short circuits can trigger it.
Common Causes
Injector-Related Causes
Injector short circuit
A short circuit inside one injector can overload the ECU driver, triggering P2146 and potentially damaging the ECU.
Other Possible Causes
ECU injector driver failure
The internal power transistor that drives injector group A has failed. This is the most common cause and requires specialist ECU repair.
Main relay or power supply fault
The relay providing power to the injector circuit has failed or has high resistance.
Wiring harness short
A short circuit in the injector wiring harness, often caused by chafing against the engine block.
Water ingress to ECU
Water entering the ECU housing can cause internal corrosion and driver failure.
Symptoms Drivers Notice
- Engine runs very rough or only on two cylinders
- Significant loss of power
- Engine management light on (often flashing)
- Engine may not start or stall immediately after starting
- Excessive smoke from exhaust
- Vehicle may enter limp mode
Vehicles Commonly Affected
Can You Still Drive with P2146?
Not recommended. P2146 often disables two cylinders simultaneously, making the vehicle unsafe to drive. If the engine management light is flashing, stop driving immediately and arrange recovery.
How Mechanics Diagnose P2146
- 1
Read all stored fault codes
P2146 often accompanies P0201/P0204. The combination helps identify whether it is an ECU or injector problem.
- 2
Check injector resistance
Measure each injector in group A. A short-circuited injector (very low resistance) can trigger P2146.
- 3
Test supply voltage at injectors
With ignition on, measure voltage at the injector connector. Should be battery voltage (12-14V).
- 4
Check main relay
Test the injector supply relay for correct operation and contact resistance.
- 5
ECU driver test
Using manufacturer diagnostic software, command each injector individually. If group A does not respond, ECU driver failure is confirmed.
Repair Solutions & Costs
ECU repair (specialist)
Specialist ECU repair to replace the failed injector driver transistor. Most cost-effective option.
ECU replacement
Full ECU replacement. Required if the ECU is beyond repair. Must be coded to the vehicle.
Replace short-circuited injector
If an injector short circuit caused the P2146, replace the faulty injector AND have the ECU checked.
Repair wiring
Repair any short circuits found in the injector wiring harness.
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
Injector replacement is required when an injector short circuit triggered the P2146. After replacing the injector, the ECU must also be tested — a short-circuited injector may have damaged the ECU driver.
Compatible Remanufactured Injectors
OEM bench-tested injectors for engines affected by P2146 — verified pricing, 12-month warranty, free UK delivery.
Siemens VDO / Continental A2C9303500080
2.0L EcoBlue Remanufactured Common Rail Injector (Ford Transit / Transit Custom / Tourneo Custom)
Fits: ADBC, ADBD, ADBE, BC2X
View injector
Siemens VDO / Continental 5WS40156Z
DW10 / 2.0 HDi / 2.0 TDCi / D4204T Remanufactured Common Rail Injector
Fits: AZWA, AZWC, D4204T, D4204T2
View injector
Bosch 0445117021
3.0L V6 TDI Remanufactured Common Rail Injector (Audi/VW/Porsche EA897)
Fits: CJGA, CJGC, CJGD, CJMA
View injector
Bosch 0445116030
Remanufactured Bosch 0445116030 diesel injector for VAG 2.0 TDI EA189 common rail applications. Direct replacement for VW Golf, Passat, Tiguan, Audi A3, A4, A5, A6, Q5, Skoda Octavia, Superb and Seat Leon with CBAB, CAGA, CAHA and CMEA engine variants. Cross-references 0445116029, 0445116004, 0986435360, 03L130277. OEM-tested and calibrated with full flow and leak-back verification on CR318 PRO test bench. Includes 12-month unlimited-mileage warranty. Supplied as an exchange unit — return your old injector within 30 days.
Fits: CAGA, CAGB, CAGC, CAHA
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: AZBA, AZBC, DW10CB, DW10CTED4
View injector
Delphi 28565336
Delphi diesel injector for VW/Audi/Seat/Skoda EA288 2.0 TDI platform
Fits: CLHB, CRKB, CXXA, CXXB
View injector
Bosch 0445116022
Bosch 0445116022 remanufactured piezo common-rail diesel injector for the Volkswagen Group 3.0 V6 TDI engine (OE 059130277BE) — Audi A4/A5/A6/A7/Q5/Q7, VW Touareg and Porsche Cayenne. Professionally tested and calibrated to OEM specification. Includes: OEM Tested, 12 Month Warranty, Free UK Delivery.
Fits: CAMA, CAMB, CAPA, CASA
View injector
Bosch 0445116035
Remanufactured Bosch 0445116035 piezo common-rail diesel injector for VW Transporter T5, Multivan, California and Amarok 2.0 TDI / 2.0 BiTDI (CAAC, CFCA, CDCA, CCHA/CCHB and related engine variants). Direct replacement for VW OE 03L130277C / 03L130855BX and Bosch cross-references 0445116034, 0445116057, 0445116058, 0986435369. OEM-tested and calibrated with full flow and leak-back verification on CR318 PRO test bench. Includes 12-month unlimited-mileage warranty. Supplied as an exchange unit — return your old injector within 30 days.
Fits: CAAC, CAAD, CAAE, CCHA
View injectorCompatible Injector Part Numbers
16 injectors compatible with engines affected by P2146.
5WS40156-Z
Siemens VDO / Continental · from £90.00
3294238468
Bosch · from £90.00
0987654567
Bosch · from £99.88
765C591356
Bosch · from £100.00
0867673265
Bosch · from £100.00
32475294386
Bosch · from £100.00
8923423466
Siemens · from £100.00
100054325
Bosch · from £100.00
A6510704987
Delphi · from £100.00
664378392
Siemens · from £100.00
28307309
Delphi · from £100.00
0445110613
Bosch · from £100.00
Cross Reference Numbers
OEM and alternative part numbers for injectors affected by P2146.
Affected Vehicle & Engine Combinations
Trusted Injector Families for These Engines
Verified remanufactured injector families fitted to engines documented to log P2146.
A2C9303500080
Siemens VDO / Continental · 2.0L EcoBlue
Engines: ADBC, ADBD, ADBE, BC2X, BCCC, BCCD
5WS40156Z
Siemens VDO / Continental · DW10 / 2.0 HDi / 2.0 TDCi / D4204T
Engines: AZWA, AZWC, D4204T, D4204T2, D4204T5, DW10BTED4
0445117021
Bosch · 3.0L V6 TDI
Engines: CJGA, CJGC, CJGD, CJMA, CKVD, CLAA
0445116030
Bosch · 2.0L TDI CR (EA189)
Engines: CAGA, CAGB, CAGC, CAHA, CAHB, CBAA
28388960
Delphi · 2.0L HDi
Engines: AZBA, AZBC, DW10CB, DW10CTED4, KLBA, LPBA
28565336
Delphi · VW/Audi/Seat/Skoda 2.0 TDI (EA288)
Engines: CLHB, CRKB, CXXA, CXXB, DBKA, DDYA
Need a Replacement Injector?
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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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