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.
DTC P1204: Vehicle Does Not Operate In CNG Mode: Description
The Powertrain Control Module (PCM) controls fuel delivery and determines which fuel system the engine is operating on. The PCM controls the Low Pressure Lock-Off (LPL) solenoid, and the High Pressure Lock-Off (HPL) solenoid. The PCM commands the HPL solenoid open for one second at every ignition ON, to prime the CNG fuel system. The PCM commands the HPL, and the LPL open, when the engine is cranking or running on CNG. If the vehicle does not start and operate on CNG within 8 seconds, this DTC will set.
NO RELATED
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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.