Oxygen Sensor Testing Information (MT 0597-06)

Publication date: 1997-05-01
Reference number: MT 0597-06

OXYGEN SENSOR TESTING INFORMATION

TECHNICAL INFORMATION TIP - MANUFACTURER

Reference Number(s): MT 0597-06, Date of Issue: May, 1997

OXYGEN SENSOR TESTING

Model(s): 1995-97 Mazda B-Series

Category: Mazda Tips

Bulletin No.: MT 0597-06

Date: May, 1997

DESCRIPTION

Vehicles with EEC-V OBD II systems have oxygen sensors upstream and downstream of the catalyst.

Upstream oxygen sensors are used for fuel rate adjustment and operate the same as oxygen sensors in EEC-IV systems.

Oxygen sensors downstream of the catalyst are referred to as catalyst monitor sensors and are used to determine efficiency of the catalyst.

When monitoring the voltage of the downstream oxygen sensors, expect to see unpredictable voltage ranging from -0.1 to 1.5 volts. It is only during the catalyst monitor test that a predictable voltage switching occurs.

NOTE: Do not replace the oxygen sensors, oxygen sensor circuits, fuel control system or PCM because the downstream sensors are not switching predictably.

If a fault is detected during the downstream oxygen sensor monitor test, a DTC will be stored in continuous memory for later retrieval.