Heater Check

Oxygen Sensor Heater For Heated Oxygen Sensor (HO2S) Before Three Way Catalytic Converter (TWC), Checking


NOTE:
- Vehicle must be raised before connector to oxygen sensor is accessible.
- When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.


Special tools and equipment
- VAG1551 scan tool (or VAG1552 mobile scan tool) with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements







- All fuses must be OK.
- Battery voltage must be at least 11.5 volts.
- Fuel Pump (FP) relay must be OK.

Test sequence
- Connect VAG1551 scan tool (VAG1552). Start engine and select the Engine Control Module (ECM) using address word 01.

Connecting scan tool and selecting ECM. Refer to " Scan Tool Testing/Scan Tool Connecting and Initial Checks " Testing and Inspection

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display:


Read measuring value block
Enter display group number XXX


- Press buttons -0-, -4- and -1- to select "Display group number 41". Press -Q- button to confirm input.

Indicated on display: (1 to 4 = display fields)


Read measuring value block 41 ->
1 2 3 4


- Check the status of the oxygen sensor heater in display field 2: Display: Htng.bef.cat.ON

Display Group 41:

If specified values are obtained:
- Press the -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.







- Disconnect 6-pin harness connector to Heated Oxygen Sensor (HO2S) -G39- (arrow).







- Set multimeter for resistance measurement and check resistance of sensor heating between terminals 3 + 4 at connector for oxygen sensor.
Specification: 2.5 to 10.0 Ohms

If a short circuit is found in the oxygen sensor heater:
- Replace Heated Oxygen Sensor (HO2S) -G39-.


NOTE: When oxygen sensor is replaced, adaptation values in the Engine Control Module (ECM) must be erased. Service and Repair


If oxygen sensor heater has continuity:

Checking voltage supply







- Set multimeter for voltage measurement and connect it to terminals 3 + 4 at connector to control module.
- Start engine, and let run at idle.
- Measure voltage supply and observe display group 41, display field 2.Htng.bef.cat.ON indicated: Specification: 11.0 to 14.5
VHtng.bef.cat.ON/Htng.bef.cat.OFF (alternating) indicated: Specification: oscillating between 0.0 and 12.0 V
- Switch ignition off.

If there is no voltage:







- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.







- Check wire between test box and 6-pin connector for open circuit according to wiring diagram. Terminal 4 + socket 5 Wire resistance: max: 1.5 Ohms

If specified value is obtained:
- Check wire between 6-pin connector terminal 3 and the Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram. Wire resistance: max: 1.5 Ohms

After successful repair:
- Read readiness code. If DTC memory was erased or the Engine Control Module (ECM) was disconnected from the continuous B+ supply, the readiness code must be re-generated. Refer to Monitors, Trip and/or Drive Cycle (Readiness Codes)/Reading Readiness Code. Testing and Inspection Refer to Monitors, Trip and/or Drive Cycle (Readiness Codes)/Generating Readiness Code. Testing and Inspection