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DTC P0172 SYSTEM TOO RICH (BANK 1)

DTC P0172 SYSTEM TOO RICH (BANK 1)

OUTLINE OF DIAGNOSIS

Detect the fuel system malfunction by the amount of main feedback control.

Diagnostic Method

Fuel system is diagnosed by comparing the target air fuel ratio calculated by ECM with the actual air fuel ratio measured by sensor.

ENABLE CONDITION

Secondary Parameters Enable Conditions
A/F main learning system

In operation

Engine coolant temperature

≥ 75°C (167°F)

Engine load

Map 5 or more

Intake air change during 0.5 engine rev.

≤ 0.01 g/rev

Learning value of EVAP conc. during purge

≤ 0.1

Cumulative time of canister purge after engine start

20 seconds or more

Continuous period after canister purge starting

30 seconds or more



Map 5

Engine speed (rpm) idle 800 1,200 1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400
Measured value (g/rev)

na

0.181

0.173

0.154

0.169

0.171

0.181

0.193

0.201

0.211

0.208



GENERAL DRIVING CYCLE

Perform the diagnosis continuously at a constant 60 km/h (37.3 MPH).

DIAGNOSTIC METHOD

Abnormality Judgment

Judge that the fuel system malfunction occurs when the time during completing the malfunction criteria below continues 30 seconds or more by comparing the diagnosed value (fsobd) with threshold value.

Judgment Value

Malfunction Criteria Threshold Value
fsobd = (sglmd − tglmda) + faf + flaf

≤ fsobdR1

where,

See Map 4

sglmd = measured lambda

fsobdR1 = rich side threshold value of fsobd

tglmda = target lambda

faf = main feedback compensation coefficient every 64 milliseconds

flaf = main feedback learning compensation coefficient



Map 4

Amount of air (g/s) 0 2.4 4.7 7 9.4 11.7
fsobdR1 (%)

−40

−40

−36.9

−32.0

−27.0

−27.0



Time Needed for Diagnosis: 10 seconds × 3 times

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

Normality Judgment

Judge OK when the malfunction criteria below are continued for 10 seconds.

Judgment Value

Malfunction Criteria Threshold Value
fsobd = (sglmd − tglmda) + faf + flaf

≥ −20%



DTC CLEAR CONDITION


• When the OK idling cycle was completed 40 times in a row

• When “Clear Memory” was performed


MALFUNCTION INDICATOR LIGHT CLEAR CONDITION


• When OK with similar drive in 3 drive cycles.

• When “Clear Memory” was performed


FAIL SAFE

Rich side malfunction


• Purge control solenoid valve control: Not allowed to purge.



• Heavy fuel judgment control: Not allowed to carry out the heavy judgment.


ECM OPERATING AT DTC SETTING


• Memorize the freeze frame data. (For test mode $02)

• Memorize the diagnostic value and trouble standard value. (For test mode $06)