Electric Exhaust Gas Recirculation System Monitor

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Electric Exhaust Gas Recirculation (EEGR) system monitor is an on-board strategy designed to test integrity and flow characteristics of EEGR system. The monitor is activated during EEGR system operation and after certain base engine conditions are satisfied. Input from ECT or CHT, IAT, TP, CPS, MAF, and MAP sensors is required to activate EEGR System Monitor. Once activated, EEGR system monitor will perform each test listed during engine modes and conditions indicated. Some EEGR system monitor tests are also performed during KOEO and KOER self-tests.

The motor EGR monitor consists of an electrical and functional test that checks motor and EEGR system for proper flow. PCM controls EEGR valve by commanding from 0-52 discreet increments or "steps" to get valve from fully CLOSED to fully OPEN position. Motor electrical test is a continuous check of 4 electric motor coils and circuits to PCM. A malfunction is indicated if an open circuit, short to power, or short to ground has occurred in one or more motor coils/circuits for a calibrated period of time. If a malfunction has been detected, EEGR system will be disabled, setting KOER, and Continuous Memory DTC P0403. Additional monitoring will be suspended for remainder of driving cycle, or until next engine start-up.
After the vehicle has warmed up and normal EEGR rates are being commanded by PCM, EEGR flow check is performed. Flow test is performed once per drive-cycle when a minimum amount of EEGR is requested and remaining entry conditions required to initiate test are satisfied. If a malfunction is detected, EEGR system as well as EEGR monitor is disabled until next engine start-up.
EEGR flow test is done by observing the behavior of 2 different values of MAP; analog MAP sensor reading, and inferred MAP reading (a MAP reading calculated from MAF sensor, TP sensor, RPM, etc.). During normal, steady-state operating conditions, EEGR is intrusively commanded ON to a specified percentage. Then, EEGR is commanded OFF. If EEGR system is working properly, there is a significant difference in both observed and calculated values of MAP, between EEGR ON and EEGR OFF states.
When flow test entry conditions have been satisfied, EEGR is commanded to flow at a calibrated test rate (about 10 percent). At this time, value of MAP is recorded (EEGR ON MAP). Value of inferred MAP EEGR ON IMAP is also recorded. Next, EEGR is commanded OFF (zero percent). Again, value of MAP is recorded (EEGR OFF MAP). Value of EEGR OFF IMAP is also recorded. Typically, 7 such ON/OFF samples are taken. After all samples have been taken, the average EEGR ON MAP, EEGR ON IMAP, EEGR OFF MAP and EEGR OFF IMAP values are stored.
The differences between EEGR ON and EEGR OFF values are calculated.
- MAP-Delta = EEGR ON MAP - EEGR OFF MAP (Analog MAP)
- IMAP-Delta = EEGR ON IMAP - EEGR OFF IMAP (Inferred MAP)
If the sum of MAP-Delta and IMAP-Delta exceeds a maximum threshold or falls below a minimum threshold, DTC P0400 (high or low flow malfunction) is stored.
As an additional check, if EEGR ON MAP exceeds a maximum threshold (BARO - a calibrated value), a DTC P0400 (low flow malfunction) is registered. This check is performed to detect reduced EEGR flow on systems where MAP pickup point is not located in intake manifold, but is located just upstream of EEGR valve in EEGR delivery tube.
NOTE: BARO is inferred at engine start-up using KOEO MAP sensor reading. It is updated during high, part-throttle or high RPM engine operation.
If inferred ambient temperature is less than 20°F (-7°C), more than 130°F (54°C), or altitude is more than 8000 feet (BARO less than 22.5 In. Hg), EEGR flow test cannot be reliably done. In these conditions, EEGR flow test is suspended and a timer starts to accumulate the time in these conditions. If vehicle leaves these extreme conditions, timer starts and if conditions permit, will attempt to complete EEGR flow monitor. If timer reaches 500 seconds, EEGR flow test is disabled for remainder of current driving cycle and EEGR monitor I/M readiness bit will be set to a "ready" condition.

DTC P1408 is like DTC P0400. It will indicate an EEGR flow failure (outside minimum or maximum limits) but is only set during KOER self test. DTC P0400 and P0403 will illuminate MIL. DTC P1408 will not illuminate MIL.