Mazda MX-6 1998, Workshop Manual, Page: 242 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
DTC P0171
P0172
P0174
P0175
P1130
P1131
P1132
P1150
P1151
P1152
Adaptive fuel control system (RH) too lean
Adaptive fuel control system (RH) too rich
Adaptive fuel control system (LH) too lean
Adaptive fuel control system (LH) too rich
Lack of heated oxygen sensor (Front RH) (H 02S 11) switch adaptive fuel at limit
Lack of heated oxygen sensor (Front RH) (H 02S 11) switch sensor indicates too lean
Lack of heated oxygen sensor (Front RH) (H 02S 11) switch sensor indicates too rich
Lack of heated oxygen sensor (Front LH) (H 02S 21) switch adaptive fuel at limit
Lack of heated oxygen sensor (Front LH) (H 02S 21) switch sensor indicates too lean
Lack of heated oxygen sensor (Front LH) (H 02S 21) switch sensor indicates too rich
DESCRIPTION
• DTC P0171 right bank and DTC P0174 left bank indicate fuel/air ratio is too lean. Fuel trim
system is at rich correction limit.
• DTC P0172 right bank and DTC P0175 left bank indicate fuel/air ratio is too rich. Fuel trim
system is at lean correction limit.
• DTCs P1130 right bank and P1150 left bank indicate fuel control system has reached
maximum compensation for lean or rich condition and heated oxygen sensor is not
switching.
• DTC P1131 right bank and P1151 left bank indicate fuel/air ratio is correcting rich for an
overly lean condition. Heated oxygen sensor voltage is less than 0.45 volt.
• DTC P1132 right bank and P1152 left bank indicate fuel/air ratio is correcting lean for an
overly lean condition. Heated oxygen sensor voltage is greater than 0.45 volt.
[Possible Cause]
Fuel System Induction System
• Excessive fuel pressure • Air leaks after MAF sensor
• Leaking fuel injector(s) • Vacuum leaks
• Leaking pressure regulator • Restricted air inlet
• Low fuel pressure or running out of fuel • Positive crankcase ventilation (PCV) system
• Contaminated fuel Injector(s) • Fuel purge system
• Improperly seated engine oil dipstick
Base Engine
• Oil overfill EGR System
• Cam timing • Leaking gasket
• Cylinder compression • Stuck open EGR valve
• Exhaust leaks before or near heated oxygen sensor’s • Leaking diaphragm
Warning
Following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following
warnings before performing fuel system service:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames
away from fuel.
• Fuel line spills and leaks are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel
can also irritate skin and eyes. To prevent this, always complete “BEFORE REPAIR PROCEDURE” and “AFTER
REPAIR PROCEDURE” described in this manual.
st
0 1 -1 4 BEFORE REPAIR PROCEDURE
c r 0 1 -1 4 AFTER REPAIR PROCEDURE
STEP INSPECTION ACTION
1
VISUAL CHECKS
• Check intake air system for leaks,
obstructions and damage.
• Check air cleaner element and air cleaner
housing for blockage.
• Verify integrity of PCV system.
• Check for vacuum leaks.
• Are any of above concerns present?
Yes SERVICE as necessary.
RESET PCM to completely clear DTCs.
w After Repair Procedure
COMPLETE OBD II Drive Mode.
RERUN OBD Test.
No
Go to next step.
0 1 -0 1 B -3 6