P0202: Injector Circuit/Open – Cylinder 2
Engine may run rough, misfire, lose power, and exhibit poor fuel economy; prolonged operation can damage catalytic converter and other components.
Overview
OBD‑II DTC P0202 indicates an electrical malfunction in the #2 cylinder fuel injector circuit—open, short, high/low resistance, or PCM driver fault—leading to rough running, misfire, and poor performance.
Common Symptoms
- Check Engine Light illuminated
- Rough or unstable idle
- Engine misfire on cylinder 2
- Reduced engine power and acceleration
- Poor fuel economy
- Possible failure of emissions inspection
Most Common Causes
Injector solenoid failure or internal fault prevents proper operation.
Broken wires, poor connections, corrosion, pin damage.
Rare but possible; requires advanced diagnostics to confirm.
High resistance at connection points can trigger code.
Power feed issues (fuse/relay) affecting injector power.
Diagnostic Steps
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Use an OBD‑II scanner to confirm P0202 and check for related codes.Expected: P0202 confirmed; no additional conflicting injector or misfire codes.Interpretation: Ensures focus on cylinder 2 injector circuit.
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Visually inspect wiring and connectors to cylinder 2 injector for damage/corrosion.Expected: Properly seated connector with no visible damage.Interpretation: Eliminates obvious wiring issues.
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Measure injector resistance with multimeter and compare to manufacturer spec.Expected: Resistance within spec range.Interpretation: Within range suggests wiring/PCM instead of injector.
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Check supply voltage at injector with ignition on; test injector signal with noid light while cranking.Expected: Appropriate battery voltage on power feed; injector pulses flagged by noid light.Interpretation: No pulses indicate driver/wiring fault; no voltage indicates power feed issue.
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Swap #2 injector with another cylinder’s injector to see if code follows.Expected: If code moves, injector is faulty; if not, harness/PCM is likely.Interpretation: Helps isolate between injector and circuit.
Repair Solutions
Cost varies by vehicle make/model and labor rates.
Depends on extent of damage and accessibility.
Requires advanced diagnostics; PCM replacement is typically a last resort.
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Replacing spark plugs/ignition parts instead of diagnosing the injector circuit.
- Assuming PCM failure without thorough wiring and injector tests.
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