3FF0

3FF0 - P0101

Information saved in
DDE

Fault code
3FF0 - P0101

Fault text
DDE: Air-mass flow sensor: Ratio of calculated to measured
air mass too high

Fault description
The diagnostic trouble code is logged in the ECU when the
ratio of the calculated to the measured air mass rises above a
limit value based on the operating point in the program map.

Condition for fault identification
Test condition:
Plausibility checks on the HFM runs during coasting/on
overrun and during the drift compensation learning phases.
The HFM plausibility check must also be enabled.
Voltage condition:
Plausibility checks on the HFM runs during coasting/on
overrun and during the drift compensation learning phases.
The HFM plausibility check must also be enabled.

Condition for fault memory entry
Debounce (4000 ms)

Action in service
1. Check boost-air temperature sensor for plausibility
(possibly indicates excessively high values, usually without
any DTC entry).
2. Check for leaks in the air-induction system between the
intake-air noise attenuator, mass-airflow sensor and
turbocharger.
3. Check air filter.
4. Examine EGR valve for sticking and to verify that it seals
when closed.
5. Check swirl valves for sticking.
6. Check intake passages and ports and exhaust valves for
carbon deposits.
If results of the tests are OK:
Replace mass-airflow sensor.

Fault effect and breakdown warning
The error disables regeneration in the particulate filter.

Driver information
Warning light:
MIL

Service instruction
none