OBD
P21B7
Cold Start Cylinder 2 Injection Timing
What it means
P21B7 stands for Cold Start Cylinder 2 Injection Timing. P21B7 is a P code, so the fault sits in the engine, transmission and emissions systems. For P21B7, the second digit places it in fuel and air metering. For P21B7, work through the cause list below, cheapest checks first.
What to check first
For P21B7, read the stored codes from every module, not just the engine, because related codes often name the same fault more precisely.
Check these first
- P21B7: Faulty or contaminated sensor in the fuel/air metering circuit
- P21B7: Damaged or shorted wiring or connector for the affected circuit
- P21B7: Vacuum leak or intake system restriction
- P21B7: Failing fuel pump, injector, or fuel pressure regulator
What to do next
P21B7 belongs to the fuel and air metering system. These are the general steps for P21B7, and the exact cause on your vehicle can differ.
- P21B7: Read freeze frame data and related codes with an OBD-II scanner
- P21B7: Inspect the affected sensor wiring and connector for damage
- P21B7: Compare live sensor readings (fuel trim, airflow, temperatures) to manufacturer specs
- P21B7: Smoke test the intake system if lean or vacuum conditions are suspected
- P21B7: Replace the failed component after confirming it with live data
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.