P0400
DTC P0400 EXHAUST GAS RECIRCULATION FLOW1. OUTLINE OF DIAGNOSIS
Detect EGR system malfunction.
Intake manifold pressure (negative pressure) is constant because the throttle valve is fully closed during deceleration fuel cut. At this time, when the EGR valve is opened/closed, the intake manifold pressure will change. EGR System OK/NG is judged by the range of this change.
2. COMPONENT DESCRIPTION
3. ENABLE CONDITION
4. GENERAL DRIVING CYCLE
During deceleration fuel cut from more than 53 km/h (approx. 33 MPH), perform diagnosis once. Be careful of vehicle speed and engine speed. (Diagnosis will not be completed if the vehicle speed and engine speed conditions become out of specification due to deceleration.)
5. DIAGNOSTIC METHOD
Measure the pressure values when the enable conditions are established, and perform diagnosis by calculating those results.
1. Label the intake manifold pressure value as PMOF1, which is observed when enable conditions are established, and set the EGR target step to 50 steps (nearly full open).
2. Label the intake manifold pressure value as PMON, which is observed after one second has passed since EGR target step was set to 50 steps (when the enable conditions were established), and set the EGR target step to 0.
3. Label the intake manifold pressure as PMOF2, which is observed after one second has passed since EGR target step was set to 0 (after two seconds have passed since the enable conditions were established).
Abnormality Judgment
Judge as NG when the following conditions are established, and judge as OK when not.
PMON - (PMOF1 + PMOF2) / 2 < 2.48 kPa (18.63 mmHg, 0.733 inHg)
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
6. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed
7. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed
8. FAIL SAFE
A/F main learning = Not allowed.
Knock learning = Not allowed.
EGR control: Operation prohibited.
9. ECM OPERATION AT DTC SETTING
- Memorize the freeze frame data. (For test mode $02)
- Memorize the diagnostic value and trouble standard value. (For test mode $06)