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Exhaust Gas Recirculation (EGR) Monitor — I/M EGR

Exhaust Gas Recirculation (EGR) Monitor

The Exhaust Gas Recirculation (EGR) system

EGR valve for Chrysler

Electrically controlled EGR valve with position sensor on the top

reduces the formation of Oxides of Nitrogen during combustion by keeping combustion temperatures below 2500°F. The EGR system accomplishes the heat reduction by recirculating a small amounts of exhaust gas back into the intake manifold at cruising speeds, where it is mixed with the incoming air/fuel mixture.

This reduces combustion temperatures by up to 500°F. The ECM determines when, for how long, and how much exhaust gas is recirculated back to the intake manifold.

How the EGR Monitor works

The EGR monitor has several ways to check system operation. It may use a position sensor on the EGR valve to determine whether the EGR opening is at the commanded position. Or, it can use a differential pressure feedback system to determine if the actual EGR flow matches what the ECM has commanded

The EGR Monitor performs EGR system function tests at preset times during vehicle operation.

The EGR Monitor is a “Two-Trip” Monitor. If a fault is found on the first trip, the computer temporarily saves the fault in its memory as a Pending Code. The computer does not command the MIL on at this time. If the fault is sensed again on the second trip, the computer commands the MIL “On,” and saves the code in its long-term memory.

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Posted on by Rick Muscoplat

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