At idle, the carbon monoxide (CO) content in the exhaust gases should be 0.5±0.2%. If it is less, this may be due to the following reasons:
- engine intake tract leak (after the air flow meter);
- additional air supply valve malfunction;
- fuel pressure regulator malfunction;
- partial clogging of the fuel filter;
- fuel pump discharge pressure does not match the nominal value;
- electronic control unit malfunction;
- malfunctions in the operation of electronic devices of the fuel injection system (to check them, use the Bosch 0.684.100.202 test device).
The reasons for increased CO levels may be:
- insufficient tightness of the oil dipstick;
- increased oil level in the oil pan;
- leaky inlet or outlet valves;
- air flow meter malfunction;
- failure to turn off the starting injector;
- malfunctions in the operation of electronic devices of the fuel injection system (to check them, use the Bosch 0.684.100.202 test device);
- leaky injectors.