Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 355 (ENGINE CONTROLS SELF-DIAGNOSTICS - 2.2L BI-FUEL)DIAGNOSTIC TESTSDTC P0201-P0204: INJECTOR CONTROL CIRCUITTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 - DTC P1020 indicates that a fuel injector circuit condition is detected while operating on CNG. If DTC P1020 and an individual fuel injector DTC are both set, diagnose P1020 first. If DTC P1020 is not set, the condition affects only the gasoline fuel injector related circuits. If DTCs P0201-P0204 are set without a DTC P1020 being set, the condition occurred during gasoline operation.
- 3 - The step determines if the condition exists. Remove the AF relay to ensure that the vehicle is operating on gasoline. Leave the relay out for the remainder of the diagnostic.
- 5 - This step verifies that an ignition voltage is supplied to the gasoline fuel injector. If the ignition voltage circuit is open a fuel injector DTC will set while operating on gasoline.
- 6 - This step tests the fuel injector and circuits to the gasoline fuel injector. If the test light blinks, then the AF injector relay and circuits are okay.
- 7 - This step tests the fuel injector control circuit from the PCM. The test light should blink while the engine is idling.
- 8 - This step tests if a ground is constantly applied to the fuel injector control circuit.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.