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P0491 - Secondary Air Injection System Insufficient Flow Bank 1 Possible causes - Intake leak - Damaged AIR system components - Faulty AIR Solenoid Valve - Faulty AIR system relay
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P0491 - Secondary Air Injection System Insufficient Flow Bank 1
Possible causes Intake leak Damaged AIR system components Faulty AIR Solenoid Valve Faulty AIR system relay
Possible symptoms Engine Light ON (or Service Engine Soon Warning Light) P0491
Description An air pump is used on the vehicle to lower tail pipe emissions on start-up. The Powertrain Control Module (PCM) grounds the Air pump relay control circuit which energizes the Air pump. The PCM also grounds the Air combination valve vacuum control solenoid circuit, which energizes the Air vacuum control solenoid. Vacuum is then applied to both Air combination valve diaphragms which opens the shut off valves. The PCM enables both circuits simultaneously when Air system operations is desired. When the AIR system is active, then Air pump forces fresh air into the exhaust stream in order to accelerate catalyst operation. The AIR combination valves replace the conventional check valves. When the AIR system is inactive the shut off valves prevent air flow in either direction.
Ok the p143 or 143e code is 02 censors ! Located on the exhaust pipe . And on BMW Is got to cost some $$$$.the p0491 Is the air intake control censer! Should be located somewhere next to the air cleaner. Hope this helps and good luck !!
I believe it could be a faulty oxygen sensor or blocked air tubes. Check to make sure air pump is operating.Check green and black wires between pcm and pump relay. Check for 12v power between these two wires with key on check the wires for damage as this has been a problem area on these vehicles. Hope this helps.
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