Buy 1990 Gmc C1500 Sierra SLX Extended Cab Pickup Fleetside 4.3L Chevrolet V6 M/T Exhaust Gas Combustion - OEM Gmc Part # 12576918 (12568582, 17113575, 17113618)

Valve. Exhaust Gas Recirculation (EGR). Throttle Position Sensor.
A Valve used to recirculate small amounts of Exhaust back into the combustion chambers of the engine in order to decrease the combustion temperature, thereby reducing the formation of smog-producing nitrogen oxides. Calif.

EGR Valve

EGR Valve - Repair or Replace
A failed EGR valve will often have no noticeable symptoms beyond a check engine light, but it does cause your 1990 GMC C1500 to operate inefficiently and produce higher emissions. Our technicians have access to manufacturer-approved repair processes and GMC genuine parts.