When I check my DTC codes with my reader I get P0410 Secondary Air Injection System. While the Check Engine Light (CEL) is on the Fuel System is running in open loop and things look fine, but when I erase the DTC, turning the CEL off the fuel system then goes into closed loop and I get a "fault with at least one oxygen sensor". There are two oxygen sensors (pre and post cat) and I just replaced both of them with $100 "Walker" Oxygen Sensors. I have also tested and found to be working my Air Pump, Relay, and SAS Valve(Air Pump Check Valve). I don't think that a ground signal is ever sent to the air pump to turn it on during normal operation, but I can ground the relay and turn the pump on by applying a ground wire myself. I can't figure it out and it's very frustrating, any help would be greatly appreciated. Thank you very much.

 

Is the coolant temp sensor readings good?

 

Yes I can read the coolant temp. and it seems to be within normal limits. I've read before that you believe that the air pump turns on based on the coolant temp.. Is that the sensor that is in fact responsible for controlling the secondary air injection system?

 

I think so. I know the coolant temp has to be below a certain spec in order for the pump to come on.

 

What is the temperature range that the coolant temperature should be in? What is the temperature that it should be below in order for the air pump to turn on? Would I get a DTC if my coolant temperature sensor was bad?

 

I will have to try to find the specific temp.
But there will not always be a code when the ECT is bad.
I will also try to dig up a wiring diagram for you.

 

tech, I would be interested in that stuff if you could find it. Thanks

 

I will try to find it tomorrow.