Vehicle Damage Warnings

AH49.10-P-1000-01A Notes for vehicles with catalytic converter
- with CODE (620a) Vehicles with catalytic converters


Ignition faults
In the event of ignition faults the catalytic converters are endangered, since the fuel/air mixture is converted in the hot catalytic converter. If severe ignition faults occur, the engine may only be operated briefly at low load. The cause of the damage must be eliminated immediately. In case of doubt, check the catalytic converters for thermal damage after eliminating the fault in the ignition system.

Checking catalytic converter system for thermal damage
The catalytic converter is damaged by thermal overload. This can be checked by a visual inspection when the exhaust system is removed. Complaints about performance after engine malfunctions indicate thermal overload of the catalytic converter. Residues of the molten catalytic converter plug up the exhaust pipe.

Fuel additives
These should be rejected on vehicles with catalytic converters. It should be borne in mind that only the specified fuel quality may be used.

Use of leaded fuel
If leaded fuel has been used inadvertently, the function of the lambda control should be checked. If the probe is defective, it must be replaced. If the emission value is exceeded, replace the entire catalytic converter system.

Engine oils
The same recommendations (approved products, oil change intervals, etc.) apply for vehicles with catalytic converters as for those without catalytic converters.

Unpleasant odors
Hydrogen sulphide can form in the catalytic converter as a result of deposits from sulphur constituents in the fuel. Hydrogen sulphide causes unpleasant odors even in the smallest concentrations, however it is not hazardous to health.

Danger of fire (stopping off highway)
The catalytic converters are thermally insulated to ensure efficient emission control under all operating conditions. Therefore when the engine is operating correctly the temperatures are not higher than with conventional muffler systems.

Excessive temperatures occur only when uncombusted fuel/air mixture enters the catalytic converter (e.g. due to fault in ignition or injection system).