Chery Fora (Elara A520). Manual — part 150

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
control valve failure and oxygen sensor failure are not appeared at the same time; if there are
failures existing at the same time please deal with other failures at first and then do as below.)

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

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

40

and observe if it is around 3.7V.

No

Diagnosis help

Yes

Repair or replace

cable

6

Check if there is open circuit or short circuit to ground

between 1

st

cylinder injector joint pin No.2 and the

ECU pin No.27.

No

Diagnosis help

DTC: P0202 The 2

nd

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 2

nd

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 2

nd

injector joint pin No.1 and main relay.

No

Next step

Yes

Next

4

Check the resistance value by multimeter between 2

nd

cylinder injector pin No.1 and No.2, and observe if it

is 11-13Ω when it is 20℃.

No

Change injector

Yes

Diagnosis help

5

Check the voltage value by multimeter between 2

nd

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

No

Next step

Yes

Repair or replace

cable

6

Check if there is open circuit or short circuit to ground

between 2

nd

cylinder injector joint pin No.2 and the

ECU pin No.6.

No

Diagnosis help

DTC: P0203 The 3

rd

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 3

rd

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 3

rd

injector joint pin No.1 and main relay.

No

Next step

Yes

Next step

4

Check the resistance value by multimeter between 3

rd

cylinder injector pin No.1 and No.2, and observe if it

is 11-13Ω when it is 20℃.

No

Change injector

Yes

Diagnosis help

5

Check the voltage value by multimeter between 3

rd

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

No

Next step

6

Check if there is open circuit or short circuit to ground

Yes

Repair or replace

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

41

cable

between 3

rd

cylinder injector joint pin No.2 and the

ECU pin No.7.

No

Diagnosis help

DTC: P0204 The 4

th

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 4

th

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 4

th

injector joint pin No.1 and main relay.

No

Next step

Yes

Next step

4

Check the resistance value by multimeter between 4

th

cylinder injector pin No.1 and No.2, and observe if it

is 11-13Ω when it is 20℃.

No

Replace injector

Yes

Diagnosis help

5

Check the voltage value by multimeter between 4

th

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

No

Next step

Yes

Repair or replace

cable

6

Check if there is open circuit or short circuit to ground

between 4

th

cylinder injector joint pin No.2 and the

ECU pin No.47.

No

Diagnosis help

DTC: P0230 Fuel pump control circuit failure

No.

Operating steps

Result

Follow up steps

1

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Next step

Yes

To step No.4

2

Take off the fuel pump relay and put ignition switch to

“ON”; check the voltage separately between fuel

pump relay power supply ends - that is relay pin No.

30 and No.86 and power supply cathode, and observe

if it is around 12V.

No

Next step

Yes

Repair or replace

the cable

3

Check if there is open circuit or short circuit to ground

of the relay power supply ends circuit.

No

To step No.2

Yes

Replace fuel

pump relay

4

Check the voltage by multimeter between fuel pump
relay control ends that is relay pin No. 85 and power

supply cathode and observe if it is around 3.7V.

No

Next step

Yes

Repair or replace

cable

5

Check if there is open circuit or short circuit to ground

or to power supply between relay control ends that is

relay pin No.85 and ECU pin No.69.

No

Diagnosis help

DTC: P0325 Knock sensor circuit failure

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

42

No.

Operating steps

Result

Follow up steps

1

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Next step

Yes

Next step

2

Take off the knock sensor joint from the cable; check

the resistance value by multimeter between knock

sensor connector No.1and No.2 and observe if it is

1MΩ.

No

Change sensor

Yes

Repair or replace

the cable

3

Check if there is open circuit or short circuit to ground

or to power supply between circuit of knock sensor

joint No.1, No.2 and ECU pin No.19, No. 20

No

To step No.2

Yes

Diagnosis help

4

Replace the knock sensor according to the regulation;

try running the vehicle and make the engine speed

exceed 2200rpm. Check if the DTC P0325 will appear

again.

No

Check if it is a

occasional fault

DTC: P0335 Crank shaft position sensor signal failure

No.

Operating steps

Result

Follow up steps

1

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Next step

Yes

Next step

2

Take off the speed sensor joint from the cable; check

the resistance value by multimeter between speed

sensor connector No.2and No.3 and observe if it is

around 770-950MΩwhen it is 20℃

No

Replace sensor

Yes

Repair or replace

the cable

3

Check if there is open circuit or short circuit to ground

or to power supply between circuit of speed sensor

joint No.2, No.3 and ECU pin No.34, No. 15

No

Next step

Yes

Diagnosis help

4

Check the flywheel signal disc if it is in good

conditions.

No

Replace signal

disc

DTC: P0336 Crank shaft position sensor signal unreasonable failure

No.

Operating steps

Result

Follow up steps

1

Connect the diagnostic tester and commutator, put

the ignition switch to “OFF”

Next step

Yes

Next step

2

Take off the speed sensor joint from the cable; check

the resistance value by multimeter between speed

sensor connector No.2and No.3 and observe if it is

around 770-950MΩwhen it is 20℃

No

Replace sensor

Yes

Repair or replace the

cable

3

Check if there is open circuit or short circuit to

ground or to power supply between circuit of speed

sensor joint pin No.2, No.3 and ECU pin No.34, No.

15

No

Next step

Yes

Diagnosis help

4

Check the flywheel signal disc if it is in good

conditions.

No

Replace signal disc