P0201Powertrain
Powertrain · SAE
Injector Circuit Malfunction — Cylinder 1
Meaning
The ECM detects an electrical fault in the cylinder 1 injector drive circuit. The ECM cannot command cylinder 1 injector correctly: the response signal falls outside expected parameters.
Common causes
- Short to ground or to supply in the cylinder 1 injector wiring
- Open in the cylinder 1 injector command wiring
- Failed cylinder 1 injector (coil shorted or open)
- Corroded, loose, or damaged cylinder 1 injector connector
- ECM cylinder-1-specific output driver failure
Symptoms
- Check-engine light on
- Constant or intermittent misfire on cylinder 1
- Engine vibration and rough idle
- Increased HC and CO emissions
- Possible smoke from exhaust
Severity
High: missing injection on cylinder 1 causes misfire, elevated exhaust gas temperature, and possible catalytic converter damage.
What to do
- Measure cylinder 1 injector resistance (spec: typically 12–16 Ω high-impedance or 1–5 Ω low-impedance)
- Check supply voltage and drive signal at the cylinder 1 injector connector
- Inspect wiring for shorts or opens
- Replace the injector if the coil is out of specification
- Swap the injector with another cylinder to determine if the fault follows the injector or stays at cylinder 1