engine code p0411
#2
RE: engine code p0411
On cold starts a pump pumps air into your exhaust to speed up catalytic converter warm up. This is the function of the secondary air injection system. It contains a pump(to pump air), a combi valve to divert air to the exhaust, and a control valve to decide how much air is pumped to the exhaust. The control valve diverts vacuum to the combi valve to open or close it. This is done from an electrical signal from the ecm. The combi vavle opens when vacuum is applyied. This allows air into the exhaust. The pump is turned on by the ecm to pump the air to the exhaust. Assuming the pump and control vavle are operating to specs, which may not be the case, the primary cause is a dirty or plugged combi valve. They have carbon buildup that prevents airflow. The combi valves are located on the rear of the head. It has one big pipe that goes to the pump. And another smaller vacuum line that goes to the control valve.
Thread
Thread Starter
Forum
Replies
Last Post