Oxygen Sensor Heater Bank 1 Sensor 1, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• Fuse -SB33- fuse 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.
• Ignition switched off.

Test procedure 

-- Observe safety precautions. Refer to SAFETY PRECAUTIONS 

-- Observe Clean Working Conditions. Refer to CLEAN WORKING CONDITIONS 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .

Start diagnosis 

-- Disconnect the HO2S Oxygen Sensor Bank 1 Sensor 1 -G39- electrical harness connector.

Checking internal resistance 

-- Using a multimeter, check the Oxygen Sensor Heater Bank 1 Sensor 1 -Z19- terminals 3 to 4 for resistance.

Specified value: 2.5 to 10.0 Ω (at approx. 20° C)

If the specification was not obtained:

-- Replace HO2S Oxygen Sensor Bank 1 Sensor 1 -G39-. Refer to the Repair information.

If the specification was obtained:

Checking voltage supply 

Start the engine.

-- Using a multimeter, check the Oxygen Sensor Heater Bank 1 Sensor 1 -Z19- electrical harness connector terminal to ground for voltage.

Oxygen Sensor Heater Bank 1 Sensor 1 -Z19- electrical harness connector terminal	Measure to
4	Ground (GND)

Specified value: above 9.5 V.

Switch the engine off.

If the specification was not obtained:

-- Check the HO2S Oxygen Sensor Bank 1 Sensor 1 -G39- electrical harness connector terminal 4 to fuse 33 in Fuse Panel B for high resistance, a short to ground, or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specification was obtained:

Checking ground activation 

If the manufacturers test box is being used. Perform the following step.

-- Install the test box.

If the manufacturers test box is not being used. Perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair information.

-- Using a multimeter, check the HO2S Oxygen Sensor Bank 1 Sensor 1 -G39- electrical harness connector to the Engine Control Module (ECM) -J623- electrical harness connector T94 terminal for resistance.

HO2S Oxygen Sensor Bank 1 Sensor 1 -G39- electrical harness connector terminal	Engine Control Module (ECM) -J623- electrical harness connector T94 terminal or test box socket
3	51

Specified value: 1.5 Ω max.

If the specification was not obtained:

-- Check the wiring for high resistance, an open or a short to voltage or ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

-- Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .

-- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to READINESS CODE .

If the DTC does return, no malfunction is detected in the wiring and the voltage supply is OK:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair information.

-- Assembly is performed in the reverse of the removal.

Final procedures 

After repair work, the following work steps must be performed in the mentioned sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .