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 P1132 & P1152: Upstream HO2S(s) Not Switching

Check air intake system for leaks and damage. Verify integrity of PCV system. Check for vacuum leaks. If any problems are found, repair as necessary. Go to step 17 . If no problems are found, go to next step.

Perform KOER Self-Test

Disconnect fuel vapor hose from intake manifold. Plug fitting at intake manifold. Start engine and run at 2000 RPM for 5 minutes, then return to idle. Perform KOER Self-Test. If DTC P1132 and/or P1152 are set, go to next step. If DTC P1132 and/or P1152 are not set, perform EVAP Leak Test to locate EVAP system leak. See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article.

HO2S Circuit Test (With Rich DTCs)

Turn ignition off. Disconnect suspect HO2S related to DTC:
- P1132, HO2S11 (Front Right)
- P1152, HO2S21 (Front Left)
With KOEO, using scan tool, select Diagnostic Data Link. Select PCM. Select PID/Data Monitor and Record. Access and observe O2S11 (Front Right) or O2S21 (Front Left) PID. If voltage is 0.2 volt or less, go to step 6 . If voltage is more than 0.2 volt, a short to power is present. Go to next step.

Check For Shorts To Voltage Source In Harness Circuit

Turn ignition off. Disconnect scan tool form DLC. Disconnect PCM connector. Install breakout box, leaving PCM disconnected.
- For DTC P1132, measure resistance between breakout box terminals No. 60 and 71 (VPWR circuit), and 93 (HTR11 circuit).
- For DTC P1132, measure resistance between breakout box terminals No. 87 and 71 (VPWR circuit), and 94 (HTR21 circuit).
If resistance is more than 10,000 ohms, replace faulty PCM. Go to step 17 . If resistance is 10,000 ohms or less, replace faulty HO2S. Go to step 17 .

Check For HO2S Signal Shorted To HO2S Heater Circuit In Sensor

Reconnect suspect HO2S connector. With KOEO, using scan tool, select Diagnostic Data Link. Select PCM. Select PID/Data Monitor and Record. Access O2S11 (Front Right) or O2S21 (Front Left) PID. If HO2S voltage is more than 0.45 volt, replace faulty HO2S. Go to step 17 . If HO2S voltage is .045 volt or less, reconnect all components. 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. Fuel pressure should be 56-72 psi (389-499 kPa). 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.

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 17 .
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 1 . Fuel injector resistance should be 11-18 ohms. If resistance is within specification, replace faulty PCM. Go to step 17 . If resistance is not within specification, go to next step.

Fig 1: Fuel Injector Harness Connector Circuit Identification
Courtesy of MAZDA MOTORS CORP.

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 1 . Record reading. Measure resistance of INJ circuit between appropriate breakout box terminal and fuel injector harness connector. See Fig 1 . 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 17 .

Check Fuel Injector Harness Circuit For Short To Power & Ground

Measure resistance between suspect INJ circuit harness connector and breakout box terminal No. 71. See Fig 1 . Record reading. Measure resistance between suspect INJ circuit harness connector and breakout box terminal No. 103. See Fig 1 . 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 17 .

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 17 .

FUEL INJECTOR FLOW RATE SPECIFICATIONS

Engine	Lbs. Hr. (kg/hr)
2.3L	21 (9.6)
3.0L	12 (5.5)
4.0L	19 (8.7)

Attempt To Generate DTCs P1131 & P1151

Disconnect suspect HO2S. Jumper HO2S harness connector SIG circuit to battery negative terminal. See Fig 2 . With KOEO, perform Self-Test. If DTCs P1131 or P1151 are set, remove jumper wire. Go to next step. If DTCs P1131 or P1151 are not set, remove jumper wire. Reconnect HO2S connector. Disconnect PCM connector Inspect PCM connector for damaged or pushed out pins, corrosion or loose wires. Repair as necessary. If PCM connector is okay, replace faulty PCM. Go to step 17 .

Fig 2: HO2S Harness Connector Circuit Identification
Courtesy of MAZDA MOTORS CORP.

HO2S Check

Connect voltmeter to HO2S connector SIG circuit and SIG RTN circuit. Disconnect any vacuum hose. Start engine and run at 2000 RPM. Observe voltage. If voltage is less than 0.4 volt within 30 seconds, reconnect vacuum hose. Go to next step. If voltage is not less than 0.4 volt within 30 seconds, replace faulty HO2S. Go to next step.

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 while wiggling, bending and shaking small sections of engine wiring harness from HO2S to PCM. Turn ignition off. If HO2S voltage stays high (more than 0.45 volt) or stays low (less then 0.45 volt), isolate cause of HO2S not switching. Repair as necessary. Go to step 17 . If HO2S voltage does not stay high (more than 0.45 volt) or stay low (less then 0.45 volt), go to next step.
NOTE: Next test step requires a helper to monitor PID.

Test Drive While Monitoring HO2S PID For Proper Switching

Using scan tool, 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.