Checking catalytic converter/lambda control

If the maximum CO value is exceeded during the CO check, the catalytic converter must be checked in the following sequence.

• Make sure that no leaded fuel has been added. The Fiat workshop can use a diagnostic tool to check the function of the lambda sensor and determine whether the engine has been operated with leaded petrol. If leaded fuel has been added, drive at least 2 tanks of unleaded fuel before replacing any components so that the injection system and exhaust system are flushed.

• Connect the CO meter, measure and record the CO content in the exhaust gas with a cold engine. Since the catalytic converter is not yet active, the CO content is well above 0.5 vol.%.

• Bring the engine to operating temperature until the radiator fan has switched on and off twice.

• Measure the exhaust gases at idle and at an engine speed of 2500 to 3000 rpm. Maximum permissible CO value: 0.3 vol.%.

• If the CO value is above 0.3 vol.%, disconnect the lambda sensor cable. The lambda sensor is located in the exhaust pipe in front of the catalytic converter housing. If the CO value is the same with the lambda sensor disconnected and connected, replace the lambda sensor, see page 123.

• Repeat the test with a new lambda sensor. If the CO value is still too high, check the following vehicle components:

• Battery voltage

• Fuel supply

• Ignition system

• Driving performance (test drive)

• Exhaust system leaks

• If no fault is found, remove the catalytic converter and check:

• Check the catalytic converter housing for damage (visual inspection);

• Tilt the catalytic converter housing. If noises can be heard, the catalytic converter core is broken.

• If damage is found, replace the catalytic converter.