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.
CNG Control Module Scan Tool Information
The Compressed Natural Gas Control Module Scan Tool Data list contains all engine-related parameters that are available on the scan tool. The list is arranged in alphabetical order.
Use the Compressed Natural Gas Control Module Scan Tool Data list only after the following is determined:
- The Diagnostic System Check - Vehicle is completed.
- No DTCs are set
- The on-board diagnostics are functioning properly
The scan tool values from a properly running engine may be used for comparison with the engine you are diagnosing. The Compressed Natural Gas Control Module Scan Tool Data list represents values that would be seen on a normally running engine.
A scan tool that displays faulty data should not be used. The scan tool concern should be reported to the manufacturer. Use of a faulty scan tool can result in misdiagnosis and unnecessary parts replacement.
Only the parameters listed below are referenced in this service information for use in diagnosis.
| Parameter | System State | Expected Value | Description |
|---|---|---|---|
| Base Operating Conditions: Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop/Accessories OFF | |||
| CNG Fuel Level | - | % | This parameter displays the amount of fuel remaining in the CNG fuel tank as measured in percentage. |
| CNG Fuel Rail Pressure | - | kPa/PSI | This parameter displays the CNG fuel rail pressure based on input from the fuel rail pressure temperature sensor. |
| CNG Fuel Rail Temperature Sensor | - | °C/°F | This parameter displays the CNG fuel rail temperature based on input from the fuel rail pressure temperature sensor. |
| CNG Injector Pulse Width | - | ms | This parameter indicates the average commanded ON time for the CNG injector pulse width. |
| Control Module Voltage Signal | - | V | This parameter displays the voltage signal sent to the CNG module. |
| ECT Sensor | - | 85 - 105°C (185 - 220°F) | This parameter displays the temperature of the engine coolant based on the input from the engine coolant temperature (ECT) sensor. |
| Engine Speed | - | RPM | This parameter displays the speed of the crankshaft as determined by the control module using an input from the CKP sensor. The scan tool will display a high value at high engine speeds and a low value at low engine speeds. |
| Fuel Mode | - | Gasoline/CNG | This parameter displays the type of fuel currently being utilized by the vehicle. |
| MAP Sensor | - | 30 - 38 kPa | This parameter displays the manifold absolute pressure (MAP) inside the engine as calculated by the engine control module based on the signal from the MAP sensor. The scan tool will display a higher value wide open throttle, and a lower value at idle. |
| Number of DTCs | - | Varies | This parameter displays the number of DTCs stored in the CNG module. |
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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.