Oxygen Sensor (O2S) 2 Heater Z28 , Checking Audi TT 8N

Note. Oxygen Sensor (O2S) 2 Heater Z28 is part of Heated Oxygen Sensor (HO2S) 2 G108 and cannot be replaced separately. When servicing electrical harness connector terminals for the Heated Oxygen Sensor (HO2S) , use only gold-plated terminals.

Special tools, testers and auxiliary items required

1. Multimeter.
2. Wiring diagram.

Test requirements

1. Fuse (on fuse panel) S243 OK.
2. Fuel Pump (FP) Relay J17 OK.
3. Battery voltage at least 12.5 volts.
4. All electrical consumers such as, lights and rear window defroster, switched off.

1. Vehicles with automatic transmission, shift selector lever into position "P" or "N".
2. A/C switched off.
3. Ground (GND) connections between engine/transmission/chassis OK.
4. Ignition switched off.

Test procedure

1. Perform a preliminary check to verify the customers complaint. Refer to --> «General Diagnosis»(ref-276276-S40851803372008010300000) .

Start diagnosis

1. Remove the engine cover with air filter. Refer to --> «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276275-S13244009452008010300000) .

Checking internal resistance

1. Disconnect the Heated Oxygen Sensor (HO2S) 2 G108 electrical harness connector - 1 -.

1. Using a multimeter , check the Heated Oxygen Sensor (HO2S) 2 G108 terminals 3 to 4 for resistance.

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

If the specification was not obtained

1. Replace the Heated Oxygen Sensor (HO2S) 2 G108. Refer to --> «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276275-S13244009452008010300000) .

If the specification was obtained

Checking voltage supply

1. Using a multimeter , check the Heated Oxygen Sensor (HO2S) G39 electrical harness connector terminal 4 to ground (GND) for voltage.

Specified value: Battery voltage.

If the specification was not obtained

1. Check the Heated Oxygen Sensor (HO2S) 2 G108 electrical harness connector terminal 3 to the Fuel Pump (FP) Relay J17 socket 23/87 an open circuit, a short circuit to each other, Battery (+), or Ground (GND).
2. Check the electrical harness connector for damage, corrosion, loose or broken terminals.
3. If necessary, repair the faulty wiring connection.

If the specification was obtained

Checking Ground (GND) activation

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

1. Install the test box VAG1598/31. Refer to --> «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276275-S13244009452008010300000) .

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

1. Remove the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .

1. Using a multimeter , check the Heated Oxygen Sensor (HO2S) 2 G108 electrical harness connector to the Motronic Engine Control Module (ECM) J220 electrical harness connector for resistance.

Specified value: 1.5 ohms max.

If the specification was not obtained

1. Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
2. Check the electrical harness connector for damage, corrosion, loose or broken terminals.
3. If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK

1. Erase the DTC memory. Refer to --> «Diagnostic Mode 04: Reset/Delete Diagnostic Data»(ref-276276-S31279847122008010300000)
2. Perform a road test to verify repair.

If the DTC does not return

Repair complete, Generate readiness code. Refer to --> Readiness Code .

1. End diagnosis.

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

1. Replace the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .
2. Assembly is performed in the reverse of the removal.

Final procedures

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

1. Check the DTC memory.
2. If necessary, erase the DTC memory. Refer to «Diagnostic Mode 04: Reset/Delete Diagnostic Data»(ref-276276-S31279847122008010300000) .
3. If the DTC memory was erased, generate readiness code. Refer to «Readiness Code»(ref-276276-S05799074302008010300000) .

End of diagnosis