Cylinder 2 Contribution/Balance Fault
A performance imbalance has been detected in cylinder 2.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer sees that cylinder 2 isn't working like the others. It's either running too lean or too rich, affecting its power, which is why you feel engine shake or poor acceleration.
What the computer is actually seeing
The engine control unit (ECU) monitors the voltage signals from the injectors and compares their contributions. If the voltage from cylinder 2's injector deviates significantly from the others, the ECU sets this code.
What a healthy reading looks like
Each cylinder should ideally have a contribution balance within ±10% of the average of all cylinders. If cylinder 2 is outside this range, it can trigger P0266.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check for any related trouble codes and clear them.
- 2Inspect cylinder 2 injector wiring and connectors for damage—ensure solid connections.
- 3Check fuel injector operation—test with a noid light or DMM, expecting a pulse and around 12V while cranking.
- 4Examine fuel pressure—should be around 50-60 PSI. If low, check fuel pump and filter.
- 5Inspect for vacuum leaks using smoke testing; focus on intake manifold near cylinder 2 and the intake gasket.
Common causes
- Fuel injector malfunction in cylinder 2
- Faulty fuel pressure regulator
- Vacuum leak affecting cylinder 2
- Bad spark plug or ignition coil on cylinder 2
- ECU software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Can I drive with P0266 active?
It's drivable, but you may notice rough running and it could worsen.
Will this come back after I clear it?
If the underlying issue isn't fixed, it'll likely reappear.
Can this code relate to other cylinders?
Yes, problems in the fuel system can affect multiple cylinders, but this code is specifically for cylinder 2.
Working a real vehicle right now?
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