Symptom Related Diagnostic Procedures

Causes of Odor

• Smell like burnt oil.

- Mostly forms in the engine compartment due to leaks on the engine or transmission.

• Sulphurous smell like exhaust.

- Due to leaks in the exhaust system.

- Through exhaust fumes, which get into the passenger compartment, for example, when driving in reverse through an exhaust gas cloud.

• Fishy smell like coolant.

- From leak at cooling system of engine or of A/C system heater core.

• If a fishy odor occurs depending on the temperature setting (weaker with temperature setting cold than with temperature setting warm), check the relevant A/C unit heater core for leaks (air does not flow constantly through heater core).

• Smell like a burned clutch.

• Evaporation from floor mats, decorative seat covers, etc.

• Dirt or moisture in the front passenger footwell or under the front seats

• In recirculation mode, the air is drawn in by the rear A/C unit from under the center console and under the front seats.

• The recirculation doors in the rear A/C unit are activated by the recirculation/fresh air door in the front A/C unit by the rear A/C display control head (E265). This means that the rear A/C unit can also be in recirculation mode when fresh air mode is set in the front. Check using Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• A rotten, moldy odor from the plenum chamber due to accumulation of various contaminants such as leaves, pine needles, etc. or water not being able to drain from the plenum chamber.

• Check plenum chamber water drains. Refer to => [ Plenum Chamber Water Drain ] Service and Repair.

• Smell from air conditioner.

• Odors originating in the front A/C unit can mainly be detected in fresh air mode and recirculation mode. If an odor occurs only in fresh air or recirculation mode, the cause is probably not the front A/C unit.

• In the case of a leaking heater core, the odor of the escaping coolant mostly depends on the temperature setting. With Cold temperature setting, air does not flow through the heater core and the odor is not as strong.

- Due to too much condensation water in A/C unit.

• Check both condensation water drains of the front A/C unit. Refer to => [ Front Condensation Water Drain Hose, Checking ] Front Condensation Water Drain Hose, Checking.

• Check both condensation water drains of the rear A/C unit. Refer to => [ Rear Condensation Water Drains, Checking ] Rear Condensation Water Drains, Checking.

- Due to an old or heavily contaminated dust and pollen filter.

• Check dust and pollen filter. Refer to => [ Dust and Pollen Filter ] Service and Repair.

- Due to deposits on evaporator fins.

• Clean evaporator with Ultrasonic HVAC Cleaning System (VAS 6189). Refer to => [ Cleaning Front and Rear A/C System Evaporator ] Service and Repair.