Chery Fora (Elara A520). Manual — part 149

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

35

at that time).

Notice: if the value always is - 40

there is perhaps

℃

open circuit failure in the circuit.

Yes

Next step

3

Take off the joint of coolant temperature sensor on

the cable, check the resistance values using

multimeter between the sensor connector No. 1 and

the No. 2 and check if it is corresponding to its

temperature (please reference the related section of

this service manual).

No

Replace sensor

Yes

To step 6

4

Take off the joint of coolant temperature sensor on

the cable, check the voltage between pin No.1 and

pin No.2 by multimeter and observe if it is around

5V.

No

Next step

Yes

Repair or replace

cable

5

Check if it is short circuit to ground between ECU

pin No.39, No. 35 and sensor connector No.1, No.2.

No

Next step

Yes

Diagnosis help

6

Start the engine at idle speed. Observe the value

changes of diagnostic tester “coolant temperature”,

the value should increase with the increase of the

engine coolant temperature.

No

Replace sensor

DTC: P0122 Indicated temperature is much lower of the air intake temperature sensor.

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

Observe “throttle valve absolute opening” item in
data flow, check the value if it is between 4% and

10% (specific data is correlated to the vehicle type).

No

To step No. 5

Yes

Next step

3

Step on the accelerator slowly to complete opening

and observe “throttle valve absolute opening” item

in data flow, check if the value is increased to around

85-90% with the opening of the throttle valve

(specific data is correlated to the vehicle type).

No

To step No. 5

Yes

Replace the sensor

4

Repeat step 3 and observe “throttle valve absolute

opening” item in data flow, and check if there is

jump during the changes.

No

Next step

Yes

Repair or replace

cable

5

Take off the joint of throttle valve positioning sensor

on the cable, check if there is short circuit to ground

between pin No.17, No.32, No.16 of ECU and pin

No.1, No.2, No.3.

No

Next step

Yes

Replace sensor

6

Check the voltage between pin No.1 and pin No.2 by

multimeter and observe if it is around 5V.

No

Diagnosis help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

36

DTC: P0123 Circuit voltage is much higher of the throttle position sensor

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

Observe “throttle valve absolute opening” item in
data flow, check the value if it is between 4% and

10% (specific data is correlated to the vehicle type).

No

To step No. 5

Yes

Next step

3

Step on the accelerator slowly to complete opening

and observe “throttle valve absolute opening” item

in data flow, check if the value is increased to around

85-90% with the opening of the throttle valve

(specific data is correlated to the vehicle type).

No

To step No. 5

Yes

Replace the sensor

4

Repeat step 3 and observe “throttle valve absolute

opening” item in data flow, and check if there is

jump during the changes.

No

Next step

Yes

Repair or replace

cable

5

Take off the joint of throttle valve positioning sensor

on the cable, check if there is open circuit or short

circuit to power supply between pin No.17, No.32,

No.16 of ECU and pin No.1, No.2, No.3 of sensor

No

Next step

Yes

Replace sensor

6

Check the voltage between pin No.1 and pin No.2 by

multimeter and observe if it is around 5V.

No

Diagnosis help

DTC: P0130 Unreasonable failure of the upstream oxygen sensor signal

(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check 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

Diagnosis help

2

Start the engine and leave it at idle speed until its

coolant reaches to the normal value. Observe the

value changes of “oxygen sensor voltage” item on

diagnostic meter, the displayed value should change

rapidly from 100mV-900mV.

No

Next step

Yes

Repair or change

cable

3

Check if there is short circuit to ground between pin

No.36, No.18, of ECU and pin A (opposite to oxygen

sensor gray connecting line), B (opposite to oxygen

sensor black connecting line).

No

Next step

DTC: P0132 Much higher voltage of upstream oxygen sensor

(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check as below.)

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

37

No.

Operating steps

Result

Follow up steps

1

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Next step

Yes

Diagnosis help

2

Start the engine and leave it at idle speed until its

coolant reaches to the normal value. Observe the value

changes of “oxygen sensor voltage” item on diagnostic

meter, the displayed value should change rapidly from

100mV-900mV.

No

Next step

Yes

Repair or change

cable

3

Check if there is short circuit to power supply between

pin No.36, No.18, of ECU and pin A (opposite to

oxygen sensor gray connecting line), B (opposite to

oxygen sensor black connecting line).

No

Diagnosis help

Yes

Check and repair

according to

diagnosis

4

A, check if the exhaust system is jammed

B, check if the injector is leaking

C, check if the fuel pressure is over higher

D, check if the valve clearance is over smaller etc.

No

Diagnosis help

DTC: P0134 Signal failure of upstream oxygen sensor

(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check 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

Diagnosis help

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, the displayed value should

change rapidly from 100mV-900mV.

No

Next step

Yes

Repair or change

cable

3

Check if there is open circuit between pin No.36,

No.18, of ECU and pin A (opposite to oxygen sensor

gray connecting line), B (opposite to oxygen sensor

black connecting line) of sensor joint.

No

Diagnosis help

DTC: P0135 Heating circuit failure of upstream oxygen sensor

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

Take off the oxygen sensor joint on the cable and

check the voltage between the pins of C (opposite to

oxygen sensor white connecting line) and D (opposite

to oxygen sensor white connecting line) by multimeter,

and observe if it is about 12V.

No

To step No.4

3

Check the resistance value between oxygen sensor

Yes

Next step

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

38

connectors C (white) and D (white) using multimeter,

and observe if it is 2-5Ω when it is 20℃.

No

Change sensor

Yes

Change fuse

4

Check the fuse inside of oxygen sensor heating circuit

and observe if it is blow.

Next step

Yes

Repair or change

cable

5

Check if there is open circuit or short circuit to power

supply between ECU pin No.1, main relay sensor

No.87 and pin C (opposite to oxygen sensor white

connecting line), D (opposite to oxygen sensor white

connecting line) of sensor joint.

No

Diagnosis help

DTC: P0171 Closed loop air fuel ratio control self adapting exceeds it maximum 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 100mV 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

Next step

Yes

Repair or replace

cable

4

Check if there is short circuit to ground 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 there is a heavy leaking in air intake system

B, check if the injector is jammed

C, check if the clearance of spark plug is too big

D, check if the sub live wire resistance is too big

E, check if the valve clearance is too big etc.

No

Diagnosis help