P0266: Cylinder 2 Contribution/Balance Fault
2 vehicles · 2 makes · $400-$5,000 repair
Most Reported On
P0266 is an OBD-II diagnostic trouble code meaning “Cylinder 2 Contribution/Balance Fault.” P0266 is a generic powertrain code indicating the engine computer detected that cylinder 2 is not contributing its expected share of power, meaning its output is unbalanced compared to the other cylinders. The PCM monitors crankshaft acceleration and fuel/injector behavior per cylinder, and an imbalance here often signals a misfire, fuel-delivery, or mechanical problem specific to cylinder 2. Left unaddressed, this can cause rough running, poor performance, and possible catalytic converter damage. This code is most commonly reported on 2005-2010 SEAT Leon (Reference, Style, FR), and 2015-2024 GMC Sierra 3500HD, with repair costs ranging from $400 to $5,000.
Common Causes
Typical Repair Cost
Based on 2 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0266, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
What does P0266 mean?
P0266 stands for "Cylinder 2 Contribution/Balance Fault." P0266 is a generic powertrain code indicating the engine computer detected that cylinder 2 is not contributing its expected share of power, meaning its output is unbalanced compared to the other cylinders. The PCM monitors crankshaft acceleration and fuel/injector behavior per cylinder, and an imbalance here often signals a misfire, fuel-delivery, or mechanical problem specific to cylinder 2. Left unaddressed, this can cause rough running, poor performance, and possible catalytic converter damage.
What are the most common causes of P0266?
The most common causes of P0266 are: Faulty or clogged fuel injector on cylinder 2, Injector wiring or connector fault, Ignition fault (coil, plug) causing a cylinder-2 misfire, Low compression / mechanical issue (valve, ring) on cylinder 2, Vacuum or intake leak affecting that cylinder, Contaminated or restricted fuel supply, PCM driver circuit fault for that injector. The specific cause varies by vehicle.
How much does it cost to fix P0266?
Repair costs for P0266 range from $400 to $5,000, depending on the vehicle and root cause.
Which vehicles are affected by P0266?
Au7o has documented P0266 across 2 vehicle models from 2 manufacturers: GMC, SEAT.
Sources (5)
- manufacturerOregon Fuel Injection: Chevrolet-GMC Diesel Diagnostics
- ForumSilveradoSierra: 6.6L Duramax Diesel blowing white smoke
- mediaChevy Trucks: The 3 Most Common Duramax L5P Engine Problems
- mediaDiesel Power Products: Common Duramax Diesel Problems & Fixes LB7 to L5P
- ForumDuramax Forum: 2015 LML blowing white smoke but why
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.