Oxygen Sensor Heater After Catalytic Converter, Checking

Special tools and workshop equipment required 

• Multimeter VAG1526 or multimeter VAG1715
• Connector test kit VAG1594
• Wiring diagram

Test requirements 

• Fuses in E-box (in plenum chamber, left) must be OK: Refer to SYSTEM WIRING DIAGRAM
  Fig 1: Identifying Fuses In E-Box (In Plenum Chamber, Left)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Motronic Engine Control Module (ECM) Power Supply Relay -J271- must be OK, check: Refer to SYSTEM WIRING DIAGRAM
• Battery voltage must be at least 11.5 volts.
• All electrical consumers such as, for example, lights and rear window defroster must be switched off.
• Parking brake must be engaged or else daylight driving lights will be switched on.
• For vehicles with automatic transmission, selector lever must be in P position.
• If vehicle is equipped with an A/C system, it must be switched off.
• Ground (GND) connections between engine and chassis must be OK.

Test sequence 

-- Disconnect 4-pin harness connector to the respective oxygen sensor:

• Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1, 4-pin harness connector 1-,
• Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2, 4-pin harness connector 3-,

Checking voltage supply and wiring to control module 

-- Connect multimeter to terminals 1 +2 of connector to Engine Control Module (ECM) for voltage measurement.

-- Start engine, and let run at idle.

Specified value: at least 7.0 V

If specified value is obtained:

-- Switch ignition off.

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If specified value is not obtained:

-- Connect multimeter to terminal 1 of connector to Engine Control Module (ECM) + Ground (GND) for voltage measurement.

Specified value: at least 11.0 V

-- Switch ignition off.

If specified value is not obtained:

-- Check voltage supply at 4-pin connector terminal 1 to Motronic Engine Control Module (ECM) Power Supply Relay -J271- according to wiring diagram: Refer to SYSTEM WIRING DIAGRAM

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If specified value is obtained:

-- Check Ground (GND) activation of the respective oxygen sensor heater.

Checking Ground (GND) activation 

-- Connect test box to control module wiring harness, connect test box for wiring test.

-- Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.

Wire resistance: max. 1.5 Ω

Component	Connector	Test box
Bank 1 sensor 2	Terminal 2	Socket 63
Bank 2 sensor 2	Terminal 2	Socket 6

-- Also check wires for short circuit to B+ or Ground (GND).

Specified value: ∞ Ω

-- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.

-- Generate readiness code.

If no malfunctions are found in wires:

-- Replace Motronic Engine Control Module (ECM) -J220- ENGINE CONTROL MODULE, REPLACING .