Mazda MX-6 1998, Workshop Manual

Page: 233 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
7 CHECK FOR SHORT IN HEATED OXYGEN
SENSOR CIRCUIT
• Key off.
• Breakout box installed. PCM disconnected.
• Measure resistance between heated
oxygen sensor signal Test Pin at breakout
box and power circuit and heated oxygen
sensor signal Test Pin and ground circuit at
breakout box.
• H 02S (Front RH)=Test Pin 60
• H 02S (Front LH)=Test Pin 87
• Power circuit=Test Pin 71/97
• Ground=Test Pin 91
• Is resistance greater than 10,000 ohms?
Yes REPLACE PCM.
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No SERVICE short circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
a-
After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
DTC P0135
P0141
P0147
P0155
Heated oxygen sensor heater (Front RH) (HTR 11) circuit malfunction
Heated oxygen sensor heater (Middle) (HTR 12) circuit malfunction
Heated oxygen sensor heater (Rear) (HTR 13) circuit malfunction
Heated oxygen sensor heater (Front LH) (HTR 21) circuit malfunction
DESCRIPTION
• DTC P0135, P0141, P0147 and P0155 indicate short to ground, or open, or short to power
in heated oxygen sensor heater circuit
[Possible Cause]
• Shorts to B+ in harness or heated oxygen sensor • Open GND circuit
• W ater in connectors • Low battery positive voltage
• Cut or pulled wires • Corrosion or poor mating terminals
• Disconnected wiring • Damaged heated oxygen sensor heater
• Open heated oxygen sensor heater power circuit • Damaged ECM/PCM
STEP INSPECTION
ACTION
1 HEATED OXYGEN SENSOR HEATER
SIGNAL CIRCUIT IS OPEN, SHORTED TO
GROUND, SHORTED TO B+ OR
EXCESSIVE CURRENT DRAW
Heated oxygen sensor reference list
DTC P0135=Heated oxygen sensor heater
(Front RH)
DTC P0141=Heated oxygen sensor heater
(Middle)
DTC P0147=Heated oxygen sensor heater
(Rear)
DTC P0155=Heated oxygen sensor heater
(Front LH)
• Visually Inspect heated oxygen sensor
circuit for exposed wiring, contamination,
corrosion and proper component.
Note
• On some applications, vehicle hoist may be
required to access heated oxygen sensor
harness.
• Were any concerns found during visual
inspection?
Yes SERVICE any concerns found in visual inspection.
RESET PCM to completely clear DTCs.
i w After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No Go to next step.
2
PERFORM KEY ON ENGINE OFF (KOEO)
SELF TEST
• Key off.
• NGS tester connected.
• Key on, engine on.
• Engine at 2,000 rpm for 1 minute.
• Key off.
• Key on, engine off.
• Perform key on, KOEO Self-Test.
• Are DTCs P0135, P0141, P0147 and/or
P0155 p resent?
Yes Go to next step.
No Fault may be intermittent.
Intermittent poor connection or component malfunction
(SERVICE or REPLACE as necessary).
Go to ENGINE SYMPTOM TROUBLESHOOTING No.27
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