Checking the heated oxygen sensor (HO2S)

WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Ignition OFF

Courtesy of VOLVO CARS OF NORTH AMERICA.

Fig 2: Disconnecting Connector

Courtesy of VOLVO CARS OF NORTH AMERICA.

Ignition off
Disconnect the connectors for the front (ECM-18) and rear (ECM-1C) heated oxygen sensor (HO2S).
Check the connectors for contact resistance and oxidation according to Contact resistance and oxidation .

Remedy as necessary.

Fig 3: Identifying Ohmmeter
Courtesy of VOLVO CARS OF NORTH AMERICA.

Was a fault detected?

YES
Refer to Verification
NO
Refer to Checking the power cable