Air Temperature Sensor Related Fault Codes

Functional description of the air temperature sensor (component B2/5b1):

The air temperature sensor (component B2/5b1) is integrated into the hot film mass air flow sensor (component B2/5). It contains a temperature dependent resistor whose resistance falls with rising temperature. The engine management system (ME9.7 Motor electronics 9.7) uses the change in the applied voltage in order to determine the air temperature.

Repair process for air temperature sensor (component B2/5b1) related fault codes:

Repair process for fault code 2025, 2026:

These fault codes are stored in case of a problem with the cables or the connectors of the intake air temperature sensor (B2/5b1).

Note:
Fault code 2026 is stored when the connector (5-pin) of the hot film mass air flow sensor (component B2/5) was unplugged during two key cycles.





Diagnostic Tree for Fault Code 2025





Diagnostic Tree for Fault Code 2026

Repair process for fault code 2029, 2030, 2032





These fault codes are stored if the measured value of the intake air temperature sensor (component B2/5b1) is implausible.

During the plausibility of intake air temperature procedure the actual value of intake air temperature (component B2/5b1) and coolant temperature (component B11/4) is compared at engine cold start. A fault code will be stored when these two temperature values are not close enough to each other. Please check component B11/4 (coolant temperature sensor) for proper operation.

Note:
Fault Code 1101, 1102, 1103, 1104, 1599, 1600, 2069, 2070 are related to the Ambient temperature display temperature sensor (component B14).





Diagnostic Tree for Coolant Temperature Sensor

If the measured value of the resistor of the intake air temperature sensor (component B2/5b1) is out of range from the specified value and all test requirements were fulfilled, replace the hot film mass air flow sensor (component B2/5) and send the part with the required DAS-printouts (refer ti Repair process for fault codes of adaptation of mixture formation) to our Quality Evaluation Center.

Note:
Before replacing the hot film mass air flow sensor, check for sand and dirt particles in the clean side (between air filter and engine) of the air intake system and clean if necessary. Check complete air intake system with air cleaner and repair as necessary.

Required DAS-printouts for warranty returns:

^ Printout of all fault codes of the ME 9.7 - Motor electronics 9.7 (Quick test).

^ Freeze frame data of all fault codes stored in the ME 9.7 - Motor electronics 9.7.

Note:
Document the value of the measured resistance and the approximate temperature of the area surrounding of component B2/5b1 for test purposes in our Quality Evaluation Center in the dealer text section of the warranty claim.

Returned hot film mass air flow sensor (component B2/5) without the required information will be debited back to the dealer as of repair date February 20, 2006.

Note:
Only original, readable printouts with the VIN number (DAS-readout) of the vehicle are accepted.