P0266 Cylinder 2 Contribution/Balance — Causes & Fix
Updated for 2026 diagnostics & repair guidance
P0266 at a Glance
What it means
The ECU has detected that cylinder 2 is contributing less power than the other cylinders.
Most common cause
Worn or failing cylinder 2 injector, causing uneven fuel delivery.
Severity
Moderate — driveable but causes rough running and increased emissions.
Can you drive?
Yes, but performance is reduced. Address within 1–2 weeks.
Typical repair cost
£100–£350 for injector replacement.
What Does P0266 Mean?
P0266 indicates the Engine Control Unit (ECU) has detected a power imbalance in cylinder 2. The ECU continuously monitors crankshaft acceleration after each cylinder fires — when cylinder 2 contributes noticeably less torque than the others, P0266 is set. This is almost always caused by a degraded injector that is delivering too little or too much fuel.
Common Causes
Injector-Related Causes
Worn cylinder 2 injector nozzle
Over time the injector nozzle wears, altering the spray pattern and reducing combustion efficiency in cylinder 2.
Injector drift (calibration loss)
The cylinder 2 injector's delivery quantity has drifted outside the ECU's compensation range, causing a measurable balance fault.
Carbon build-up on injector tip
Carbon deposits on the injector nozzle restrict fuel flow and distort the spray pattern, reducing cylinder 2 output.
Other Possible Causes
Low compression in cylinder 2
Worn piston rings or valves in cylinder 2 reduce compression, preventing proper combustion regardless of injector quality.
Glow plug failure (cylinder 2)
A failed glow plug in cylinder 2 can cause cold-start misfires that set a contribution fault code.
Symptoms Drivers Notice
- Rough idle with a rhythmic miss
- Slight vibration through steering wheel at idle
- Reduced power under acceleration
- Marginally higher fuel consumption
- Engine management light illuminated
- Occasional puff of black or white smoke
Vehicles Commonly Affected
Can You Still Drive with P0266?
Yes — P0266 is driveable. You'll notice rough idle and slightly reduced power but no immediate safety risk. Address within 1–2 weeks to prevent DPF problems from incomplete combustion. If idle becomes very rough or you notice heavy smoke, have it inspected sooner.
How Mechanics Diagnose P0266
- 1
Read cylinder contribution values
Use a diagnostic tool to read live cylinder balance data. Cylinder 2 will show a negative deviation (e.g., -15% or worse).
- 2
Perform injector leak-off test
Measure fuel return from the cylinder 2 injector. Elevated return (>15ml/min) confirms injector wear.
- 3
Swap injectors between cylinders
Swap cylinder 2 injector with a known-good cylinder. If the fault follows the injector, it's confirmed as the cause.
- 4
Check injector coding
Verify the injector IMA/QR code for cylinder 2 is correctly programmed in the ECU. Incorrect coding causes balance faults.
- 5
Compression test cylinder 2
If the injector checks out, perform a compression test to rule out mechanical wear in cylinder 2.
Repair Solutions & Costs
Replace cylinder 2 injector
The most common fix. A remanufactured injector restores correct fuel delivery and cylinder balance.
Injector cleaning (ultrasonic)
If carbon build-up is the cause and the nozzle isn't worn, professional cleaning can restore performance.
Re-code injector to ECU
If the injector is physically fine but incorrectly coded, reprogramming the IMA code resolves the balance fault.
Replace glow plug (cylinder 2)
If the glow plug has failed, replacement resolves cold-start misfires that set the contribution code.
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
Replacement is required when the leak-off test shows elevated return flow, the cylinder contribution is more than 15% below average, or the injector has more than 100,000 miles of use.
Compatible Remanufactured Injectors
OEM bench-tested injectors for engines affected by P0266 — verified pricing, 12-month warranty, free UK delivery.
Bosch 0445110369
VW/Audi 2.0 TDI (EA189/EA288) Remanufactured Common Rail Injector
Fits: CDLC, CFFA, CFFB, CFFD
View injector
Bosch 0445110351
1.3L Multijet/JTD/TDCi/HDi/DDiS Remanufactured Common Rail Injector
Fits: 1.3JDTM, 1.3JTD, 1.3SDE, 169A1.000
View injector
Bosch 0445110375
Remanufactured Bosch 0445110375 diesel injector for Renault, Nissan and Vauxhall 2.0 dCi (M9R) and 2.3 dCi (M9T) applications. Direct replacement for Renault Trafic, Master, Nissan Primastar, NV400 and Vauxhall Vivaro, Movano. Cross-references 0445110634, 0986435205, 0986435234, 166005070R, 8200912052 and 93168212. Not interchangeable with Continental/Siemens M9T variants or newer Euro 6 Bosch injectors. 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: M9R630, M9R692, M9T670, M9T672
View injector
Siemens VDO / Continental 562002010
Renault / Nissan 2.3 dCi (M9T) Remanufactured Common Rail Injector
Fits: M9T700, M9T702, M9T704, M9T706
View injector
Siemens VDO / Continental A2C59511612
1.4L HDi/TDCi Remanufactured Common Rail Injector (PSA DV4 — Peugeot/Citroen/Ford/Mazda/Toyota)
Fits: 2WZTV, 8HT, 8HX, 8HZ
View injector
Siemens VDO / Continental 562001910
Renault / Nissan / Vauxhall 2.3 dCi (M9T) Remanufactured Common Rail Injector
Fits: M9T678, M9T680, M9T686, M9T694
View injector
Bosch 0445110188
Remanufactured Bosch 0445110188 diesel injector for PSA 1.6 HDi, Ford 1.6 TDCi, Volvo 1.6 D2 and Mazda 1.6 diesel applications. Direct replacement for Peugeot 307, 308, 407, Partner, Citroen C4, C5, Berlingo, Ford Focus, C-MAX, Volvo S40, V50 and Mazda 3. Cross-references 0445110136, 0986435090, 1980H3, 1980E5, 3M5Q-9F593-CA, 30757314. 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: 9HY, 9HZ, G8DA, G8DB
View injector
Siemens VDO / Continental A2C59511316
Jaguar / Land Rover / PSA 2.7 TDV6 (DT17) Remanufactured Common Rail Injector
Fits: 276DT, AJD, AJTDV6, DT17BTED4
View injectorCompatible Injector Part Numbers
2 injectors compatible with engines affected by P0266.
Cross Reference Numbers
OEM and alternative part numbers for injectors affected by P0266.
Affected Vehicle & Engine Combinations
Trusted Injector Families for These Engines
Verified remanufactured injector families fitted to engines documented to log P0266.
0445110369
Bosch · VW/Audi 2.0 TDI (EA189/EA288)
Engines: CDLC, CFFA, CFFB, CFFD, CFFE, CFGB
0445110351
Bosch · 1.3L Multijet/JTD/TDCi/HDi/DDiS
Engines: 1.3JDTM, 1.3JTD, 1.3SDE, 169A1.000, 169A5.000, 199A3.000
0445110375
Bosch · 2.0L / 2.3L dCi
Engines: M9R630, M9R692, M9T670, M9T672, M9T676, M9T690
562002010
Siemens VDO / Continental · Renault / Nissan 2.3 dCi (M9T)
Engines: M9T700, M9T702, M9T704, M9T706, M9T710, M9T716
A2C59511612
Siemens VDO / Continental · 1.4L HDi/TDCi
Engines: 2WZTV, 8HT, 8HX, 8HZ, DV4C, DV4TD
562001910
Siemens VDO / Continental · Renault / Nissan / Vauxhall 2.3 dCi (M9T)
Engines: M9T678, M9T680, M9T686, M9T694, M9T696, M9T698
Need a Replacement Injector?
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Fault Codes
Symptoms
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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