Chery A15 / 480 LHD model. Manual - part 87
Diagnostic trouble code: P0172 “Self adapting of closed loop control for air fuel
ratio exceeding the lower limit”
(Note: The following diagnostic procedures are applicable only under the
circumstances that the trouble codes of intake air pressure sensor, carbon canister
control valve, oxygen sensor and so on do not appear simultaneously, in case that such
trouble codes appear at same time, overhaul shall be carried out based on the
following procedures after dealing with other malfunctions firstly.)
Item
No.
Operation procedure
Inspection
results
Follow-up
procedure
1
Connect the diagnostic tester and adaptor,
and turn the ignition switch to “ON”
position.
Proceed to next
step.
Yes
Proceed to next
step.
2
Start up the engine, run at idle speed until
the temperature of coolant reaches the
normal value.
Under the full load working condition
observe the value of “Oxygen sensor
voltage” to verify that the indicated value
is maintained at 900 mV without
significant change for long time under
certain working conditions.
No
Refer to diagnosis
help.
Yes
Proceed to next
step.
3
Connect the fuel pressure gauge to the
feeding pipe of fuel supply system to
observe whether the fuel pressure is
maintained at 350kPa under full load
working condition.
No
Check and repair
the fuel system.
Yes
Repair and replace
the wiring harness.
4
Verify that the circuits between 36# and
18# pins of ECU and A# (corresponding
to the grey connecting wire of oxygen
sensor) and B# (corresponding to the
black connecting wire of oxygen sensor)
are short to power supply.
No
Proceed to next
step.
Yes
Carry out service
based on the
diagnostic results.
5
A. Verify that there is leakage in the fuel
injector;
B. Whether there is air leakage in
exhaust pipe;
C. Whether the ignition timing is correct;
D. Whether the air intake valve conduit
is worn out;
E. Whether the valve clearance is
excessive small;
And etc.
No
Refer to diagnosis
help.