Mazda 6 2002 - Dtc P0171

F116
ON-BOARD DIAGNOSTIC
End Of Sie
DTC P0171
A6E397001084W27
6 INSPECT GAS LEAKAGE FROM EXHAUST
SYSTEM
• Visually check if any gas leakage is found
between exhaust pipe and rear HO2S.
• Is there any gas leakage?
Yes Repair or replace any faulty exhaust parts, then go to Step
9.
No • Inspect the following harnesses for open or short to
ground circuit, repair or replace harness if necessary.
 Rear HO2S terminal A (harness-side) to PCM
terminal 1Y (harness-side)
• Repair or replace harness if necessary.
• If all items above are okay, replace faulty sensor.
Then go to Step 9.
7 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 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?
Note
• Large bubbles are normal since they are
remaining air coming out from engine
coolant passage.
Yes Air gets in from poor sealing on head gasket or other areas
between combustion chamber and engine coolant
passage.
Repair or replace faulty parts, then go to Step 9.
No Go to next step.
8 INSPECT ENGINE COMPRESSION
• Inspect engine compression.
(See B9 COMPRESSION INSPECTION.)
• Is it okay?
Yes Go to next step.
No Implement engine overhaul for repairs, then go to next
step.
9 VERIFY TROUBLESHOOTING OF DTC P0140
COMPLETED
• Make sure to reconnect all disconnected
connectors.
• Turn ignition key to ON (Engine OFF).
• Clear DTC from memory using WDS or
equivalent.
• Perform KOER self-test.
(See F66 KOEO/KOER SELF-TEST.)
• Is same DTC present?
Yes Replace PCM, then go to next step.
(See F43 PCM REMOVAL/INSTALLATION.)
No Go to next step.
10 VERIFY AFTER REPAIR PROCEDURE
• Perform After Repair Procedure.
(See F66 AFTER REPAIR PROCEDURE.)
• Is there any DTC present?
Yes Go to applicable DTC troubleshooting.
(See F67 DTC TABLE.)
No Troubleshooting completed.
STEP INSPECTION ACTION
DTC P0171 Fuel trim system too lean
DETECTION
CONDITION
• PCM monitors short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) values during closed loop
fuel control. If fuel trim exceeds preprogrammed criteria, PCM determines that fuel system is too lean.
Diagnostic support note
• This is a continuous monitor. (FUEL SYSTEM)
• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one
drive cycle while the DTC for the same malfunction has been stored in the PCM.
• PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.