Secondary Air System- Invalid Signal code

i have the same issue with my '98 f355 - i have a tubi/hyper-flow cat set up
can't seem to shake the p1448

any input would be appreciated

-T

 

I show P1448 as
Catalyst Bypass Flap Circuit Malfunction (sig/min/max)
Check wiring
Check the valve
Check vacuum leakage
Check functionality in diagnosis mode

 

Hi Tariq,

Did you try pulling out the panel with the thermal ECUs and vacuum valves on it and cleaning all of the contacts? I could only reach the plugs for the two valves when you visited. My car is now showing a P1448 as well and I can make it appear by wiggling the wiring to the panel. Maybe one of the thermal ECUs on that panel is somehow involved in generating the P1448 code. You could switch the two ECUs (just swap the plugs between them) to see if that changes anything. If those ECUs do affect the P1448, then it will change to a P1445 if the ECU is the problem.

Tom

 

If it is not setting a light it is not considered a failure.

Errors get set in memory all the time. There is a reason there is a different threshold between putting something in memory and setting a light.


Leave it alone.


I wish they had never starting selling scanners.

 

hey tom -

yes - i did clean the contacts
i even had my tech look for leaks in the evap system (he could not find any)
i tried a brand new fuel cap as well - there was no difference made with this

brian - i should state that the cel light came on (p1448 displayed on the scanner)

-T

 

I also got a CEL light the last time I had the P1448 problem about a year ago. I switched the ECUs and got a P1445, then switched back and didn't have the problem reappear until now. My car is in the shop getting the leather worked on right now, but when I get it back I'm going to spend time on the P1448 and P0102 issues. I may need to sell the car soon, so I need to work out the final kinks.

 

tom -

let me know what you come up with.
sell the car? say it ain't so...

-T

 

P1448. I had that...it is either a bad exhaust valve, or you need to replace the cat ECU. Mine was the cat ECU, fixed it right up. But beware, with this problem, it can be intermittent, and not trip the light right away. In other words, if it is a bad cat ECU they can be flakey and not repeat their problems consistently or reliably.

 

thank you for the tip
i will get a hold of new cat ecu's and see if the p1448 goes away

 

Also make sure your exhaust bypass valve is functioning correctly. That it is closed at idle, and opens under full throttle above (approx) 3800 rpm on up.

 

bypass valve functions correctly - i can hear it open up at close to 4k rpm

-T

 

Wouldn't wiring the valve open cause the P1448 by itself? I would think so.

 

Wow sounds familiar, just got a P1448 CEL today. Sounds like the valve is working ok but I need to investigate further. Of course tried the optimistic fix first...erase the code and hope it doesn't come back