DTC P0402: Exhaust Gas Recirculation (EGR) Flow Excessive Detected
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
P0402 - EXHAUST GAS RECIRCULATION (EGR) FLOW EXCESSIVE DETECTED
| Description: | The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the differential pressure feedback EGR (DPFEGR) signal at idle and compares it to the stored signal measured during key on engine off (KOEO). The test fails when the signal at idle is greater than at KOEO by a calibrated amount. | ||
| Possible Causes: |
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| Diagnostic Aids: | A DPFEGR PID reading that is greater at idle than during KOEO by 0.5 volt or a rough engine idle may indicate a hard fault. | ||
| Application | Key On Engine Off | Key On Engine Running | Continuous Memory |
| Vehicles with an EGR system module (ESM) | - | GO to HH: Exhaust Gas Recirculation System Module (ESM) STEP HH11. | GO to HH: Exhaust Gas Recirculation System Module (ESM) STEP HH11. |
| All others | - | GO to HE: Exhaust Gas Recirculation (EGR) Systems STEP HE12. | GO to HE: Exhaust Gas Recirculation (EGR) Systems STEP HE12. |