Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Mass Air Flow Sensor, Checking
Observe all safety precautions: SAFETY PRECAUTIONS
View clean working conditions: CLEAN WORKING CONDITIONS
Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .
Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor -G70-.
Special Tools And Workshop Equipment Required
- Multimeter.
- Wiring diagram.
Test Requirements
- The Mass Air Flow (MAF) Sensor -G70- fuse 1 in Fuse Panel C is OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground connections between engine/transmission/chassis OK.
- Coolant Temperature at least 55° C.
- Ignition switched Off.
Test Procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Start Diagnosis
-- Connect the scan tool.
-- Start engine and let it run at idle.
-- Using the scan tool, Check the air flow quantity of the Mass Air Flow (MAF) Sensor -G70- at idle:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Air flow quantity at Mass Air Flow (MAF) sensor | ||||
|
6.50 to 8.2 g/sec. | |||
If The Specified Value Was Obtained: Condition Is Not Present At This Time.
-- Check the electrical harness connector at the ECM and sensor for damage, corrosion, loose or broken terminals.
-- Check the intake duct for air leaks, loose connections.
If The Specified Value Was Not Obtained:
Checking voltage supply
-- Disconnect the Mass Air Flow (MAF) Sensor -G70- electrical harness connector.
-- Start the engine and let it run at idle.
-- Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 5 to engine Ground for voltage.
Specified Value: Battery Voltage.
-- Switch the ignition OFF.
If the specified value was Not obtained:
-- Remove fuse 1 (2010 Models) or fuse 15 (2011 Models) in Fuse Panel C. Refer to Appropriate Wiring Diagrams for fuse locations. Check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 5 to Fuse 1 or 15 in Fuse Panel C for an open circuit, high resistance or short to ground.
Specified Value: 1.5 Ω Max.
-- If necessary, repair the faulty wiring connection.
If The Specified Value Was Obtained:
Checking electrical circuit
-- Start the engine and let it run at idle.
-- Using a multimeter, connect black lead to ground and red lead to terminal 1, 2 and 4 of the MAF connector and check for voltage using the chart below.
Specified Values:
| Mass Air Flow (MAF) Sensor -G70- terminal: | Specified voltage |
|---|---|
| 1 | 4.94 V (+/-.5 V) |
| 2 | 4.97 V (+/-.5 V) |
| 4 | Near 0 V |
-- Switch the ignition OFF.
If The Specified Value Was Not Obtained:
Checking wiring
-- Remove the Motronic Engine Control Module (ECM) -J623-.
-- Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T94 terminals for an open circuit. Refer to Appropriate Wiring Diagrams for Pin locations.
| Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals | Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminals |
|---|---|
| 1 | 18 |
| 2 | 23 |
| 4 | 39 |
Specified Value: 1.5 Ω Max.
If The Specified Value Was Not Obtained:
-- Check the wiring for an open, high resistance or short circuit.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If No Malfunction Is Detected In The Wiring And The Voltage Supply Was OK:
-- Replace Mass Air Flow (MAF) Sensor -G70- Refer to the Repair information.
If No Malfunction Is Detected In The Wiring And The Voltage Supply Was Not OK:
-- Replace the Motronic Engine Control Module (ECM) -J623-.
Final Procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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