Mazda 3 Workshop Manual page 114

Mazda 3 Workshop Manual – Engine + Wiring Diagrams + Diagnostic Trouble Codes
VERIFY CURRENT INPUT SIGNAL
STATUS
• Warm up engine.
• Access O2S12 PID using WDS or
equivalent.
• Verify PID while racing engine at least 10
times (in NEUTRAL (MTX) or PARK (ATX)).
• Is PID normal?
- More than 0.55 V at least once
during engine racing
INSPECT INSTALLATION OF REAR HO2S
• Inspect if rear HO2S is loosely installed.
5
• Is sensor installed securely?
INSPECT GAS LEAKAGE FROM
EXHAUST SYSTEM
• Visually inspect if any gas leakage is found
6
between exhaust pipe and rear HO2S.
• Is there gas leakage?
INSPECT SEALING OF ENGINE COOLANT
PASSAGE
Warning
• Removing radiator cap when
radiator is hot is dangerous. Scalding
coolant and steam may shoot out
and cause serious injury.
• When removing radiator cap, wrap
7
a thick cloth around and turn it
slowly.
• Remove radiator cap.
• Implement procedure to bleed air from
engine coolant, then run engine at idle.
• Is there any small bubble, which makes
engine coolant white at filling opening?
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No Go to the next step.
Yes Go to the next step.
Install sensor securely, then go to Step 9.
No
(See REAR HEATED OXYGEN SENSOR
(HO2S) REMOVAL/INSTALLATION
Repair or replace any malfunctioning exhaust
Yes
part, then go to Step 9.
• Inspect the following wiring harnesses for
open circuit or short to GND in wiring
harness.
- Rear HO2S terminal A (wiring
harness-side) to PCM terminal 2K
(wiring harness-side)
No
• Repair or replace wiring harness if
necessary.
• If all items above are normal, replace the
malfunctioning sensor.
Then go to Step 9.
Air gets in from poor sealing on head gasket
or other areas between combustion chamber
and engine coolant passage.
Yes
Repair or replace the malfunctioning part,
then go to Step 9.
No Go to the next step.
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