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.
- Verify Related Pending & Stored DTCs
If any other DTCs are present during QUICK TEST, go to appropriate procedure. If no other DTCs are present during QUICK TEST, go to next step. - Identify Trigger DTC For Freeze Frame Data
If DTC P1130 or P1150 are on Freeze Frame Data, go to next step. If DTC P1130 or P1150 are not on Freeze Frame Data, go to trouble shooting procedure for DTC that triggered Freeze Frame Data.NOTE: It is necessary to address all Continuous Memory ignition and misfire DTCs if they were received during Continuous Memory testing before addressing any KOER HO2S DTCs. - DTCs P1130 & P1150: Fuel System Not Switching At Fuel Trim (Rich Or Lean)
Check air cleaner housing and filter for blockage. Check air intake system for leaks and damage. Check PCV system. Check vacuum leaks. If any problems are found, repair as necessary. Go to step 16 . If any problems are not found, go to next step. - Check HO2S Ability To Generate A Voltage More Than 0.5 Volt
Inspect HO2S harness for chafing, burned wiring or other damage. Repair as necessary. Disconnect suspect HO2S connector. Connect DVOM to HO2S signal circuit and HO2S SIG RTN or HO2S GND at HO2S connector (component side). See Fig 1 . Run engine at 2000 RPM for 3 minutes. Run KOER Self-Test and monitor HO2S voltage. Turn ignition off. If voltage is more than 0.5 volt during or at end of Self-Test, go to next step. If voltage is not more than 0.5 volt during or at end of Self-Test, replace faulty HO2S. Go to step 16 . - Monitor HO2S PID for Proper Switching
With KOER and engine at operating temperature, using scan tool, select Diagnostic Data Link. Select PCM. Select PID/Data Monitor and Record. Access O2S11 (Front Right) or O2S21 (Front Left) PID and monitor while wiggling, bending and shaking small sections of wiring harness between HO2S and PCM. Turn ignition off. If HO2S voltage stays high (more than 0.45 volt) or low (less than 0.45 volt), isolate cause and lack of HO2S switching. Repair as necessary. See WIRING DIAGRAMS article. Go to step 16 . If HO2S voltage does not stay high (more than 0.45 volt) or low (less than 0.45 volt), go to next step.WARNING: Fuel system retains fuel pressure with engine not running. Use caution when working on fuel system. - Check Fuel Pressure
Install fuel pressure gauge. With KOEO, using scan tool, select Diagnostic Data Link. Select PCM. Select Active Command Modes. Access Output Test Mode and run fuel pump to obtain maximum fuel pressure. Fuel pump will run for approximately 8 seconds when Output Test Mode is activated. See FUEL PRESSURE SPECIFICATIONS table. If fuel pressure is within specification, fuel system is okay. Go to next step. If fuel pressure is not within specification, see FUEL DELIVERY SYSTEM under SYSTEM TESTS.FUEL PRESSURE SPECIFICATIONSEngine psi (kPa) 2.3L 35-55 (240-380) 3.0L & 4.0L 30-65 (207-448) - Check Injector Fault PIDs
Using scan tool, access INJ1F-INJ6F PIDs. If an injector fault is present, go to next step. If an injector fault is not present, go to step 12 .NOTE: Next test step erases Continuous Memory DTCs. - Check Fuel Injector(s) & Harness Resistance
Turn ignition off. Disconnect PCM connector. Install breakout box, leaving PCM disconnected. Use injector fault PID to determine which fuel injector(s) to test. Measure resistance of suspect fuel injector between INJ circuit and breakout box terminal No. 71 (VPWR circuit). See Fig 2 . See FUEL INJECTOR RESISTANCE SPECIFICATIONS table. If resistance is within specification, replace faulty PCM. Go to step 16 . If resistance is not within specification, go to next step.FUEL INJECTOR RESISTANCE SPECIFICATIONSEngine Ohms 2.3L 11-13 3.0L 8.5-15.5 4.0L 11-18 - Check Fuel Injector Harness Resistance
Disconnect fuel injector harness connector at suspect fuel injector. Measure resistance of VPWR circuit between breakout box terminal No. 71 and fuel injector harness connector. See Fig 2 . Record reading. Measure resistance of INJ circuit between appropriate breakout box terminal and fuel injector harness connector. See Fig 2 . Record reading. If each resistance is less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open wiring harness. See WIRING DIAGRAMS article. Go to step 16 . - Check Fuel Injector Harness Circuit For Short To Power & Ground
Measure resistance between suspect INJ breakout box terminal and breakout box terminal No. 71. See Fig 2 . Record reading. Measure resistance between suspect INJ circuit breakout box terminal and breakout box terminal No. 103. See Fig 2 . Record reading. If each resistance reading is more than 10,000 ohms, go to next step. If either resistance reading is 10,000 ohms or less, repair short circuit. See WIRING DIAGRAMS article. Go to step 16 . - Flow Test Fuel Injector(s)
Using a fuel injector tester, flow test fuel injectors following equipment manufacturers instructions. See FUEL INJECTOR FLOW RATE SPECIFICATIONS table. If flow rate values are within specification, go to next step. If flow rate values are not within specification, replace faulty fuel injector(s). Go to step 16 .FUEL INJECTOR FLOW RATE SPECIFICATIONSEngine Lbs. Hr. (kg/hr) 2.3L 21 (9.6) 3.0L 12 (5.5) 4.0L 19 (8.7) - Inspect Induction System For Air Leaks
Inspect the following areas for signs of air leaks:- Inlet tube(s) from air cleaner to throttle body assembly.
- Gaskets between upper and lower intake manifold assemblies.
- Vacuum hoses and lines for cracks and proper connections.
- PCV system integrity.
- Check Cylinder Compression
Check cylinder compression. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES article. If cylinder compression is within specification, go to next step. If cylinder compression is not within specification, repair as necessary. Go to step 16 .NOTE: Next test step requires a helper to monitor PID. - Test Drive While Monitoring HO2S PID For Proper Switching
Using scan tool, select Diagnostic Data Link. Select PCM. Select PID/Data Monitor and Record. Access O2S11 (Front Right) or O2S21 (Front Left) PID. While observer monitors PID, test drive vehicle under different road conditions in an attempt to simulate original fault. If HO2S appears to properly switch, unable to duplicate fault at this time. Go to next step. If HO2S does not appear to properly switch, replace faulty HO2S. Go to next step. - Verify Trouble Shooting Of DTCs Completed
Reconnect all electrical connectors. Perform QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, trouble shooting is complete.