Catalyst Temperature Sensor 1, Checking

Catalyst Temperature Sensor 1, Checking

Observe all safety precautions: => [ Safety Precautions ] Generic Scan Tool

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Perform a preliminary check to verify the condition: => [ Preliminary Check ] Preliminary Check.

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools, testers and auxiliary items required

• Multimeter

• Electrical connector test lead set

Test conditions

• Battery voltage 12.5 V

• Fuse OK

• Engine MUST be at room temperature.

• Ignition switched off

Test procedure

- Engine MUST be at room temperature.

- Disconnect the Catalyst Temperature Sensor l (G20) connector.- 1 -






- Using a multimeter, check the Catalyst Temperature Sensor l (G20) terminals 1 to 2 for resistance.

Specified value: 230 ohms (+/- 60 ohms) at room temperature.

If the specified value was Not obtained:

- Replace the Catalyst Temperature Sensor l (G20)

If the specified value was obtained:

- Turn the ignition switch ON.

- Using a multimeter, check the Catalyst Temperature Sensor l (G20) terminals 1 to 2 for voltage.

Specified value: 3.32 V (+/-.4 V)

If the specified value was Not obtained:

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

- Using a multimeter, check the Catalyst Temperature Sensor l (G20) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T94 terminals for an open circuit according to the wiring diagram.






Specified value: 1.5 ohms Max.

If the specified value was Not obtained:

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

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

- If necessary, repair the faulty wiring connection.

If there was no fault found in the wiring and the voltage was not obtained:

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

Final procedures

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

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning.