Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
- If QUICK TEST was not performed, go to QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
- DTCs P0131 & P0151: Contaminated HO2S/Voltage Shift
Inspect HO2S connector for water. If water is not in HO2S connector, go to next step. If water is in HO2S connector, repair connector as necessary. Replace HO2S. Go to step 4 . - Verify Wiring Is In Proper Pin Location
Disconnect PCM connector. Install breakout box, leaving PCM disconnected. Measure resistance of HO2S SIG circuit between breakout box terminal No. 60 (DTC P0131) and HO2S harness connector (Gray/Light Blue wire) or terminal No. 87 (DTC P0151) and HO2S harness connector (Red/Black wire). See Fig 1 . Record reading. Measure resistance of SIG RTN circuit between breakout box terminal No. 91 and HO2S harness connector (Orange wire). Record reading. If either resistance is less than 5 ohms, replace faulty HO2S sensor. Go to next step. If either resistance is 5 ohms or more, repair wiring as necessary. See WIRING DIAGRAMS article. Go to next step. - Verify Trouble Shooting Of DTCs Completed
Make sure all electrical connectors are reconnected. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If the same DTC is present, replace faulty PCM. Repeat QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, test is complete.