Exhaust Gas Recirculation (Egr) System - Honda Prelude 1993 Service Manual

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Exhaust Gas Recirculation (EGRI System
Troubleshooting Flowchart
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The Malfunction Indicator Lamp (MlL) indicates Diagnostic Trouble Code (DTC) 12: A problem in
. L-l!J _ the Exhaust Gas Recirculation (EGR) system.
The EGR system is designed to reduce oxides of nitrogen emissions {NOx) by recirculating exhaust gas through the EGR
valve and the intake manifold into the combustion chambers. lt is composed of the EGR valve. EGR vcuum cont.ol valve.
EGR control solenoid valve, ECM and various sensors.
The ECM memory contains ideal EGR valve lifts tor varying operating conditions. The EGR vslve lilt sensor detects the
amount of EGR valve lift and sends the information to the ECM. The ECM then compares it with the jdeal EGR valve
lift which is determined by signsls sent from the other sensors. lf there is any di{ference between the two, the ECM
varies current to the EGR control solenoid valve to further regulate vacuum applied to the EGR valve.
EGR
CONTROL
sol-Et{otD
VALVE
BLK/YEL ---l>
ECU IECMI {15 A}
EGB
VACUUM
CONTROL
VALVE
BLK
I
I
:
{cont'd)
RED/
EGR VALVE 5-J WHT
LIFT SENSoR I.+-WHT/BLK
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