Error code

OBD2 P0266

OBD2P0266
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Cylinder 2 Contribution/Balance.

Severity

moderateCan drive but may experience reduced performance and fuel economy.

Summary

P0266 indicates that cylinder #2 is not contributing properly to engine balance and efficiency. This issue can be detected by the ECM using sensors like the crankshaft position sensor (CKP).

Symptoms

  • Reduced engine performance
  • Poor fuel economy
  • Rough idle

Common Causes

  • Dirty or clogged fuel injectors
  • Improper replacement of fuel injectors without proper learning procedure
  • Mechanical issues such as worn rings, burnt valves, or leaking head gasket

Diagnosis

  1. Check for corrosion or water damage in the fuel injector and driver connectors
  2. Compare waveforms of cylinder #2 fuel injector with its neighbors using a digital oscilloscope
  3. Perform cylinder compression and leakdown tests to identify mechanical issues

Fixes

  • Clean or replace the fuel injectors

FAQ

What does P0266 mean?

P0266 indicates that cylinder #2 is not contributing properly to engine balance and efficiency.

How do I diagnose P0266?

Diagnose by checking fuel injectors, comparing waveforms with a digital oscilloscope, and performing compression tests.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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