Diagnostics, closed loop
Courtesy of SAAB-SCANIA OF AMERICA, INC.
- At a correction factor of 0.75, the system will read a rich air/fuel mixture and the fuel quantity has been reduced as much as possible. If this state persists for longer than 20 seconds, diagnostic trouble code P1172 will be generated. The fault can be caused by the following:
- Air leak between the compressor and the throttle.
- Purge valve stuck open.
- Defective mass air flow sensor.
- Fuel pressure too high.
- Correspondingly, at a correction factor of 1.25, the system will read a lean air/fuel mixture and the fuel quantity has been increased as much as possible. If this state persists for longer than 20 seconds, diagnostic trouble code P1171 will be generated. The fault can be caused by the following:
- Air leak after the throttle.
- Low fuel pressure.
- Defective mass air flow sensor.
- Blocked injectors.
- If closed loop fails to be activated within a reasonable time after start, diagnostic trouble code P0125 will be generated.