1. Make sure that leaded gasoline has not been filled into the tank when refueling. In RENAULT workshops, using a diagnostic tool, you can check the lambda probe and determine which fuel is filled. If there is leaded fuel in the tank, at least two fills must be completely used up before replacing parts (two full tanks) unleaded gasoline. This is necessary for «flushing» injection and exhaust systems.
2. Connect a gas analyzer and measure the CO content in the exhaust gases on a cold engine. Record the resulting value. Due to the fact that in this case the catalyst has not yet started to work, the CO content will exceed 0.5%.
3. Warm up the engine to operating temperature so that the radiator fan turns on and off twice.
4. Measure the CO content at engine speeds of 2500-3000 rpm. The maximum allowable value should be 0.3%. If the CO content is above 0.3%, then disconnect the wire from the lambda probe. The lambda probe is located in the exhaust pipe before the catalytic converter. If the CO content is still the same after switching off the lambda probe as it was when the sensor was connected, the lambda probe must be replaced.
5. Install a new lambda probe and repeat the CO check. If it still exceeds the nominal value, then the following systems or parts should be checked:
- voltage (charging) battery;
- fuel supply;
- ignition system;
- engine operation at different speeds (test drive);
- tightness of the exhaust system.
If no defects are found during this check, then remove the catalyst and inspect it for damage to the housing.
6. Turn the catalyst from side to side. If characteristic noises are heard inside the catalyst, this means that its internal filling is broken. In this case, the catalyst must be replaced.