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 53 km/h (approx. 33 MPH) or more, 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. Name the intake manifold pressure value as PMON one second after the target EGR step is set to 50 (when the enabled conditions were established). Then set the target EGR step to 0.
3. Name the intake manifold pressure value as PMOF2 one second after the target EGR step is set to 0 (two seconds after the enabled conditions were established).
Abnormality Judgment
Judge as NG when the following conditions are established.
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
Normality Judgment
Judge as OK and clear the NG if the following conditions are established.
Time Needed for Diagnosis: 1 time