Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0125
Insufficient engine coolant temperature for enter a closed loop fuel control
DESCRIPTION
• DTC P0125
indicates
ECT
sen sor has not achieved required tem pe rature to en ter closed
loop operating conditions within specified amount of time after starting engine. This code
will light the MIL
[Possible Cause]
• Insufficient warm up time • Low coolant
• Leaky or stuck open thermostat
STEP INSPECTION
ACTION
1 DTC P0125 INDICATES EXCESSIVE TIME
TO ENTER CLOSED LOOP FUEL CONTROL
• Check coolant level.
• Is coolant level correct?
Yes Check thermostat.
c r 0 1-12 THERMOSTAT INSPECTION
No FILL to proper level.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
COMPLETE Comprehensive Component Monitor Drive
Mode.
RERUN OBD Test.
DTC P0133
Heated oxygen sensor (Front) (H 02S 11) circuit low response
DESCRIPTION
• DTC P0133 indicates response rate of heated oxygen sensor is below some calibrated
window
[Possible Cause]
• Contaminated heated oxygen sensor • MAF sensor
• Exhaust leaks • Air leaks
• Shorted/Open wires • Deteriorating heated oxygen sensor
• Improper fueling
STEP
INSPECTION ACTION
1 PERFORM KOER SELF TEST
• Key on, engine running and engine at
operating temperature.
• Activate KOER self-test.
• Is DTCs P1127 present during KOER
self-test?
Yes Go to DTC chart and service DTCs P1127 as necessary.
No Go to next step.
2
HEATED OXYGEN SENSOR RESPONSE
TEST
• Key off.
• NGS tester connected.
• Key on, engine off.
• Select Generic OBD II function from menu
and trigger.
• Press Continue.
• Select Diagnostic Monitoring Test Results
from menu and trigger.
• Scroll to Test ID: 01 trigger and press start.
•
Does the measured value indicate
greater than 614?
Yes RESET PCM to completely clear DTCs.
tr After Repair Procedure
COMPLETE OBD II Drive Mode.
REPEAT step 1.
If test results indicate pass, testing is complete.
No Oxygen sensor test results indicate a fail.
Go to next step.
3 CHECK FOR SOURCE OF POTENTIAL
HEATED OXYGEN SENSOR
CONTAMINATION
• Investigate following items as potential
source of heated oxygen sensor
contamination.
• Use of unapproved silicone sealers
• Fuel contaminated by silicone additives
• Excessive oil burning (i.e. rings, valve
seals and oil overfill)
• Glycol (antifreeze) leaking internally in
engine
• Contaminated fuel
• Use of unapproved cleaning agents
• Are any of above conditions present?
Yes SERVICE source of contamination.
REPLACE heated oxygen sensor and oil/filter.
RESET PCM to completely clear DTCs.
w After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No Go to next step.
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