Mass Airflow Sensor ( T126 )
If there are additional fault codes for the mass air flow sensor, T126, fix those first. Check the mass air flow sensor and its connections for an electrical fault. Check for leaks in the EGR system or intake air system Check the exhaust pressure sensor T125, boost pressure sensor T122 and boost temperature sensor T121. Note Always perform a reset of adaption values of the mass air flow sensor if the mass air flow sensor is replaced, or if a leak in the engine intake system have been fixed For EUV engines: If the operating time with the error code active is more than 10 hours, the EGR cooler should be drained because it is likely that the condensation has formed in the air-cooled EGR cooler when the EGR system has been turned off. Perform emptying according to the instructions in the Service Manual, section 01-65. To verify that the fault is fixed, carry out a free acceleration and check that the MAF signal moves
What you'll see
No driver-visible symptom recorded.
System reaction
The ECU turns off the EGR system. Engine power is reduced Depending on the legal requirements for the engine it may not be possible to erase the fault code if it is active.
Diagnostic depth
A fault has been found with the measurement of the mass air flow
Faulty Mass Air Flow Sensor (T126) Leakage in gas exhange system ( boost side ) Other sensors in the gas exchange system eg exhaust pressure sensor T125, boost pressure sensor T122 and boost temperature sensor T121 Leak in the EGR system For EUV engines: If the operating time with the error code active is more than 10 hours, the EGR cooler should be drained because it is likely that the condensation has formed in the air-cooled EGR cooler when the EGR system has been turned off. Perform emptying according to the instructions in the Service Manual, section 01-65. To verify that the fault is rectify, frivarva engine and check that the MAF signal on the move