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.
Fuel System Pressure Release
Connect scan tool to communicate with Alternative Fuel Engine Control Module (AF ECM). Store Diagnostic Trouble Code (DTC) information. Clear DTC information and turn ignition off. Start and idle engine. Ensure engine is running on CNG by observing that Fuel Indicator Light (FIL) is off. Using scan tool, select high-pressure lock-off relay function. Command lock-off relay OFF and observe fuel tank pressure sensor data. When engine stalls or switch-over to gasoline occurs, turn ignition off and remove CNG 20-amp fuse. A small amount of CNG will remain in lines. Slowly loosen fitting to release existing line pressure.
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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.