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CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM 39 DTC: P0172 Closed loop air fuel ratio control self adapting exceeds it minimum limit (Notice: below diagnosis flow is fit for when air intake pressure sensor failure, canister No. Operating steps Result Follow up steps 1 Connect the diagnostic tester and commutator, put the ignition switch to “ON”
Next step Yes Next step 2 Start the engine and leave it at idle speed until its coolant temperature reaches to the normal value. Observe the value changes of “oxygen sensor voltage” item on diagnostic meter, and the displayed value keeps around the value of 900mV at some working conditions. No Diagnosis help Yes Repair or replace the cable 3 Connect the fuel pressure meter (connection position is the front end of fuel distributing pipe assembly fuel intake pipe); start the engine and check the fuel pressure at idle speed conditions if it is around 260kpa; take off the vacuum pipe on fuel pressure regulator, check the pressure and observe if it is around 300kpa. No Check and repair fuel system Yes Repair or replace cable 4 Check if there is short circuit to power supply between ECU pin No.36, No.18 and pin A (opposite to oxygen sensor gray connecting line), pin B (opposite to oxygen sensor black connecting line) of sensor joint. No Next step Yes Repair according to diagnosis data 5 A, check if the injector is leaking B, check if the exhaust pipe is jammed C, check if the valve clearance is too small etc. No Diagnosis help DTC: P0201 The 1 st cylinder injector circuit failure No. Operating steps Result Follow up steps 1 Connect the diagnostic tester and commutator, put the ignition switch to “ON”
Next step Yes To step No.4 2 Take off the 1 st cylinder injector joint from the cable, check the voltage value between this joint pin No.1 and the power cathode by multimeter and observe if it is 12V. No Next step Yes Repair or replace the cable 3 Check if there is open circuit or short circuit to ground between the 1 st injector joint pin No.1 and main relay. No Next step Yes Next step 4 Check the resistance value by multimeter between 1 st
cylinder injector pin No.1 and No.2, and observe if it is 11-13Ω when it is 20℃. No Change injector 5 Check the voltage value by multimeter between 1 st
cylinder injector pin No.2 and power supply cathode, Yes Repair according to diagnosis data |