Mazda MX-6 1998, Workshop Manual, Page: 86 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP
INSPECTION
ACTION
2
CHECK FOR HEATED OXYGEN SENSOR
MONITOR DTC
Note
• Incorrect heated oxygen sensor signal
input (e.g. rich/lean input signal when
engine is operating under lean/rich
conditions) may cause an abnormal
temperature increase in catalyst.
Note
• Non-California applications will not have
active Heated Oxygen Sensor Monitor. As
result, Catalyst Efficiency Monitor DTC can
be generated for rear heated oxygen
sensor concern. To check for heated
oxygen sensor concerns, go to heated
oxygen sensor inspection. If any
repairactions are necessary procedure, run
KOER self-test to verify repair. If repair
actions are not necessary, go to step 3.
• Were any of following heated oxygen
sensor monitor DTCs recorded in step
1: P0136?
Yes
Go to appropriate DTC test.
No
Go to next step.
3 CHECK FOR ECT SENSOR DTCS
Note
• ECT sensor DTCs can indicate that
thermostat is not operating correctly or that
engine coolant level is not filled to
specifications. Resulting in above normal
operating temperatures.
• Were any of following ECT sensor DTCs
recorded: P0117, P0118, P0125 and
P1117?
Yes
Go to appropriate DTC test.
No Go to next step.
4 CHECK FOR ANY OTHER DTCS
•
Were any other DTCs recorded in step
1?
Yes Go to appropriate DTC test.
No Go to next step.
5
CHECK DOWNSTREAM HEATED OXYGEN
SENSOR WIRING AND PCM
CONNECTIONS
Note
• If of downstream heated oxygen sensor
continuous are interchanged or crossed,
Catalyst Efficiency Monitor Test will fail.
• Inspect wiring of each rear heated oxygen
sensor for proper routing and connection.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion and loose wires,
etc. Service as necessary.
• Are there any wiring or connection
concerns?
Yes SERVICE any wiring or connection concerns.
For PCM pin concerns, REPLACE PCM.
RECONNECT all components.
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No No PCM root causes related to DTCs or symptoms.
Go to next step.
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