Mass Air Flow Sensor, Checking: Notes
The Mass Air Flow (MAF) sensor signal is used by the control module to calculate the permissible injection quantity and to regulate Exhaust Gas Recirculation (EGR). The smaller the MAF sensor signal is, the lesser fuel may be injected.
Cylinder bank 1 is located in direction of travel, right.
Cylinder bank 2 is located in direction of travel, left.
Use only gold-plated terminals when servicing terminals in harness connector.
Special tools and workshop equipment required
- Multimeter VAG1526 or Multimeter VAG1715
- Connector test kit VAG1594
- Wiring diagram
Test Prerequisites
- Fuses in E-box (plenum chamber, left) must be OK: Refer to SYSTEM WIRING DIAGRAM
- Battery voltage must be at least 11.5 volts.
- All electrical consumers such as, for example, lights and rear window defroster must be switched off.
- For vehicles with automatic transmission, selector lever must be in P.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- Coolant temperature must be at least 80°C DIAGNOSTIC MODE 01 - READ CURRENT SYSTEM DATA .
Mass Air Flow Sensor 1, Test Sequence
Function Test
-- Connect diagnostic tester.
-- Start engine and let run at idle.
-- Depress accelerator pedal to approx. 1500 RPM.
-- Under address word 33, select "Diagnostic mode 1: Check measured values."
-- Select the measuring value "PID 16: Air flow quantity at Mass Air Flow (MAF) sensor".
-- Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor at idle:
Specified value: 4.50 to 7.00 g/sec
-- End diagnosis and switch ignition off.
If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) sensor:
-- Check voltage supply of Mass Air Flow (MAF) sensor.
If specified value is not obtained:
-- Check signal and Ground (GND) wires of Mass Air Flow (MAF) sensor MASS AIR FLOW SENSOR, CHECKING .
Checking Voltage Supply
-- Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor -G70- (-B-).
-- Switch ignition on.
-- Measure voltage supply for MAF sensor between the following connector terminals:
| Connector on Mass Air Flow (MAF) Sensor -G70- Terminal | Specified value: | |||
|---|---|---|---|---|
| 2 + Ground (GND) | approx. battery voltage | |||
| 2 + 3 | approx. battery voltage | |||
| 4 + Ground (GND) | approx. 5 V | |||
| 4 + 3 | approx. 5 V | |||
-- Switch ignition off.
If specified values are obtained:
-- Replace Mass Air Flow (MAF) Sensor -G70-.
-- Erase DTC memory of Engine Control Module (ECM) DIAGNOSTIC MODE 04 - ERASE DTC MEMORY
-- Generate readiness code READINESS CODE .
If specified values are not obtained, check Signal and Ground Wires