Downstream Heated Oxygen Sensor - Mazda B-Series 1997 Workshop Manual

ON-BOARD DIAGNOSIS SYSTEM
p 1
OXYGEN SENSOR
Symptom
H02S output voltage is less than calibrated functional window.
between engine and end of catalyst may cause this DTC.
ACTION
lnspect downstream H02S harness for pinched, shorted
and corroded pins.
lnspect for exhaust leaks and contaminated or defective
sensor.
Are any of the above concerns present?
Key OFF.
Install breakout box, leave PCM disconnected.
Disconnect downstream H02S connector.
Measure resistance between H02S SIG test pin 35 and
SIG RTN test pin 91 at breakout box.
Measure resistance between H02S SIG test pin 35 and
VPWR 71 or 97 and VREF test pin 90 at breakout box.
Measure resistance between H02S SIG test pin 35 and
PWR GND test pin 24, 76 and 103 at breakout box.
Is resistance greater than 10,000 ohms?
Yes
Repair or replace as necessary.
,
Go to step 8.
Yes
I
Go to next step.
1
No
Key OFF.
Disconnect downstream H02S connector.
Jumper VPWR to H02S SIG circuit at H02S connector.
Key ON.
Access H02S PID or 0 2 s on scan tool.
Is H02S PID greater than 1.5 volts?
Repair short circuit.
Go to step 8.
Key OFF. Yes
1
Go to next step.
Yes Replace H02S.
Go to step 8.
- -
R~~~~~ open clrcult
Go to step 8
- -
Go to step
7.
Go to next step.
Remove breakout box and reconnect PCM.
Go to next step.
- -
~~~l~~~ PCM
Go to step 8
Leave PCM and H02S disconnected.
Measure
resistance
between H02S SIG test pin 35 at
+
breakout box and H02S SIG at H02S connector. Measure
NO
res~stance between H02S SIG RTN test pin
91
at
breakout box and H02S SIG RTN at H02S connector
Replace PCM.
Go to step 8.
Is resistance less than 5 0 ohms?
- -
Key OFF.
Reconnect PCM and H02S connector.
Key ON, engine off.
Access H02S PID or 0 2 s on scan tool.
Is the voltage greater than 1.5 volts?
Key OFF.
Key OFF.
Connect PCM to vehicle harness connector.
Disconnect downstream H02S connector.
Key ON.
Measure voltage between SIG RTN at H02S connector
and battery negative terminal.
Measure voltage between H02S SIG at H02S connector
and battery negative terminal.
Is voltage greater than 1.5 volts?
Yes
No
Yes
Yes
Connect PCM to breakout box and disconnect veh~cle
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harness from breakout box.
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Measure resistance between SIG RTN test pin 91 and
PWR GND test pin 24, 76 and 103 at breakout box.
Is resistance less than 5.0 ohms?
1
Replace PCM.
Go to step 8.
Replace H02S.
Go to step 8.
Perform After Repair Procedure to ensure customer's concern has been resolved.
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