Oxygen Sensor Heater Before Catalytic Converter, Checking
The Oxygen Sensor (O2S) Heater -- is part of Heated Oxygen Sensor (HO2S) -- and cannot be replaced separately.
When servicing electrical harness connector terminals for the Heated Oxygen Sensor (HO2S) --, use only gold-plated terminals.
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test Requirements
- Fuse (in fuse panel) -SA16- OK.
- Engine Control Module (ECM) Power Supply Relay -J363- OK.
- Battery voltage at least 12.5 V.
- 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 (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.
Test Procedure
-- Perform a preliminary check to verify the customer's complaint. Refer to PRELIMINARY CHECK .
Voltage for Oxygen Sensor (O2S) Heater --Z19-- (bank 1, sensor 1) and Oxygen Sensor (O2S) Heater --Z28-- (bank 2, sensor 1) is supplied through the the Engine Control Module (ECM) Power Supply Relay -J363-.
Start diagnosis
-- Disconnect the 6-pin electrical harness connector -1- from the Heated Oxygen Sensor (HO2S) --G39-- and Oxygen Sensor (O2S) Heater --Z19-- (bank 1, sensor 1).
To test the Oxygen Sensor (O2S) Heater --Z28-- (bank 2, sensor 1), perform the following steps:
-- Remove the screw -arrow- retaining the coolant reservoir.
-- Disconnect the electrical connector from Engine Coolant Level (ECL) Warning Switch -F66- at the bottom of the coolant reservoir and set aside the coolant reservoir with the coolant hoses -1- and -2- connected.
-- Disconnect the 6-pin electrical harness connector -1- from the Heated Oxygen Sensor (HO2S) --G108-- and Oxygen Sensor (O2S) Heater --Z28-- (bank 2, sensor 1).
Checking internal resistance
-- Using a multimeter, check the Heated Oxygen Sensor (HO2S) -- terminals 3 to 5 for an open circuit.
| Heated Oxygen Sensor (HO2S) -- Terminals |
|---|
| 3 to 5 |
Specification: 2.5 to 10 Ω (at room temperature).
If the specification is not obtained:
-- Replace the Heated Oxygen Sensor (HO2S) --G39-- (bank 1, sensor 1) or Heated Oxygen Sensor (HO2S) --G108-- (bank 2, sensor 1) before catalytic converter. Refer to Component Locations Overview
If the specified value is obtained:
Checking voltage supply
-- Using a Multimeter --, check the electrical harness connector terminals for voltage.
| Electrical harness connector | Specified value |
|---|---|
| 3 to 5 | Battery voltage |
-- Operate the starter briefly.
Specified value: battery voltage.
-- Switch the ignition off.
If no voltage is present:
-- Using a multimeter, check the Heated Oxygen Sensor (HO2S) -- electrical harness connector terminal 5 to ground (GND) for voltage.
-- Turn key on.
| Harness connector Terminal | Measure to |
|---|---|
| 5 | Engine Ground (GND) |
-- Operate the starter briefly.
Specified value: Battery voltage.
-- Switch the ignition off.
If there is no voltage again:
-- Using a multimeter, check the wiring connection from the Heated Oxygen Sensor (HO2S) -- electrical harness connector terminal to the Engine Control Module (ECM) Power Supply Relay -J363- terminal through the fuse for resistance.
| Heated Oxygen Sensor (HO2S) -- Electrical Harness connector terminal | Engine Control Module (ECM) Power Supply Relay -J363- terminal |
|---|---|
| 5 | 2 |
Wiring resistance: 1.5 Ω max.
-- If necessary, repair the wiring connection.
-- If the wiring is OK:
Check Ground (GND) activation
-- Using aMultimeter --, check the Heated Oxygen Sensor (HO2S) -- electrical harness connector terminal to Ground (GND) for voltage.
| Harness connector terminal | Measure to |
|---|---|
| 3 | Ground (GND) |
-- Operate the starter briefly (engine can also start)
Specified value: Battery voltage, possibly fluctuating.
-- Switch the ignition off.
If the specification is not obtained:
If the manufacturers test box is being used, perform the following step.
-- Install the test box VAG1598/42. Refer to Component Locations Overview .
If the manufacturers test box is not being used, perform the following step.
-- Remove the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING .
-- Using a multimeter, check the Heated Oxygen Sensor (HO2S) -- electrical harness connector to the Engine Control Module (ECM) -J623- electrical harness connector for resistance.
Oxygen Sensor (O2S) Heater --Z19-- (bank 1, sensor 1):
| Heated Oxygen Sensor (HO2S) --Z19-- Electrical Harness Connector Terminal | Engine Control Module (ECM) -J623- Electrical Harness Connector Terminal |
|---|---|
| 3 | 51 |
Oxygen Sensor (O2S) Heater --Z28-- (bank 2, sensor 1):
| Heated Oxygen Sensor (HO2S) --Z28-- Electrical Harness Connector Terminal | Engine Control Module (ECM) -J623- Electrical Harness Connector Terminal |
|---|---|
| 3 | 73 |
Specified value: 1.5 Ω max.
If the specification is not obtained:
-- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
-- If necessary, repair the wiring connection.
If no malfunctions are detected:
-- Replace the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING
-- Assembly is performed in the reverse of the removal.
After 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 .