I have a 2005 xB with a Check engine light with the code P0505 that keeps coming up.

my car was previously turbo'd with a haltech stand alone engine management and the CEL was always on for various reasons and I never payed attention to it.

As of a week ago, I brought it back to stock, respliced in all the wires from the Haltech ecu back to the stock ecu (using butt end connectors) and added all the factory parts back in the car. The car runs perfect, no idle issues, no cold start idle issues. After the swap back, I was originally slightly low on coolant and the dealer thought the code might have been from the bubble in the coolant line, so they refilled it and re-scan'd it. They still got the code and said it was the idle control valve. I sourced a used one and swapped it out and cleared the code again, but the same code quickly popped back up.

what else could be the problem? could the resplicing of the wire next to the ecu cause resistance issues enough to throw the code?

I really don't know what else to check at the moment...

thanks for any help that can be provided!

 

Check your wires going to your IAC (Idle Speed Control). Hopefully its just not getting power, if not its bad. It is a small part under the throttle body.

Good luck.

 

yeah, that was the part that I completely swapped out. It has a coolant inlet and outlet on it and mounts under the throttle body.

the cold start idle still works perfectly fine. It still idles slightly high upon cold start up and lows as the car warms up. so it makes me think it might be something else?

 

redo the patches , get rid of the butt splices and just solder the connections. The sensors are really sensitive as to the voltage they see and a little change could cause it to be mis-read.

 

QFT! Get rid of those butt connectors and soldier them properly and make sure you use heat shrink on those wires! The ECM is looking for certain resistances and voltages and those butt connectors (and sometimes even soldier) adds resistance to the circuit.

 

im having the same exact problem, the same situation but with an XA. the only difference in problem is that my car is idling like a chainsaw! ive gone through everything, double and triple checked. and the auto shop isnt helping much at all. i don't have the money to keep going back and having my car checked. can anyone help?

 

Maybe the O2 sensors got cooked when turboed and don't like running NA. How does the exhaust smell? Burning any oil or running lean or rich? Everyone do an ECU reset to get the engine management retrimmed.

 

exhaust smells usual, and i'm not too savvy with the comps on the scions nor any car in general quite yet, how do you reset the ECU?

 

nvmd fig'd it out. easier than i was thinking.

 

Hey, how did you fix your CEL?

 

its not fixed... i reset my ECU and it brought me temporary relief, but now my cars gone back to its crazy idling. only thing that i've found strange and that is different is my light isn't on, i'm not pulling any codes and its been bout 350 miles. still in need of some help or some sort of a checklist to run through if anyones familiar with this code and its causes.

 

lights been off for about a moth now but my idling is still the same. and ive noticed its been running realy rich lately and im only gettin bout 19-25mpg with a feather foot. mechanics shop is useless with my prob.

 

I swapped out the complete exhaust including o2's from a stock one. I swapped the IAC, and it ran fine (200 miles without codes) until I noticed I had a small leak from a hose that was not completely tight. I retightened it, but I may have caused an air bubble. ever since, I the CEL keeps coming back right away. did I possibly cook another IAC just by having an air bubble?