2a+RoN

Okay, my car was throwing code 11, intake air thermosensor. So I ordered the sensor from Mazdaformance last week and installed it this weekend. I cleared the ECU and started her up and the light was still on. So today I pulled the manifold again and checked out the sensor with a multimeter and it all checked out. I even checked the old one and it was even still good! DAMN! There's $50 spent for no reason but my own stupidity.

Anyways, with both sensors good, I can only blame the code on bad wiring going to the sensor or the connector. Is there any way to test the connector and the wires? I stripped crappy plastic shielding on the wires as far back as I could with the harness still in the car and it all looked Okay. I was wondering how I can go around this? Can I just bypass the stock wiring harness and tap into the wire at the ECU then run it direct to the sensor?

Thanks,
Aaron

P'cola FD

Look through the FSM, and find out exactly which pins go to the ecu for the IAT sensor. Take your ohm meter, and test the resistence of the wires from the ecu to the connector for the sensor. If there is no continuity, then run new wires through the firewall, to the proper ecu pins. It will be a pain in the ***, but it beats the price of a new harness.

2a+RoN

Ok thanks, I'll do that.

SBi_Owner

I don't know if this helps....

The green wire on the Temp sensor goes to pin 3L on the ECU.

The brown/blue stripe goes to pin 4D on the ECU.

Now, pin 4D also has the water thermo switch, throttle sensor, EGR, metering oil pump, and the pressure sensor on that circuit.

Now, you can try to use the Brown/blue stripe wire from the EGR switch(you probably don't even have the plug in use) and attach it to the temp sensor same wire. Try starting the car and watch for the code. If the code comes back, you can run a wire from pin 3L, of the ECU, to the Green wire on the temp sensor.

It sounds like a lot of BS, but it will let you know if it is the wiring in the car.

Just my 2 cents....

Adam

daem0n

Hey Aaron, I have a similar problem to this but I was afraid it was from some rewiring I did to the sensor and have had the car garaged since winter so I haven't had a chance to iron the problem out yet. Did you notice that the car went into limp mode when this happened? When my check engine light would flash and I checked it for codes, I would get code 11 but the car seemed to run decently. It ran a little better when the ECU was reset but when the ECU stored the code I still got boost fine and everything.

2a+RoN

I went through the manual last night and checked the wires with my multimeter. Well sure enough the green going to 3L was no good and had no resistance. I just ran a new one and everything is all good now, no check lights, YAY! Thanks!

daem0n, my car was running as you describe, wouldn't go into limp mode and ran fine I thought. However, it was running crazy rich in comparison to now, just from the smell of the exhaust. I suggest using a multimeter like P'cola suggested, worked great for me.

igottafc

iTrader: (6)

is it fine to run the car with a bad sensor like this because im getting a code 11 as well. This wouldnt happen to cause the car to run rich would it? -alex

daem0n

igottafc - yes, running this code will cause your car to be running rich. It's not great for the car and you should probably fix it since it will clog your cat, plus it's just not getting the best performance out of your car.

Also, Aaron, thanks for the information. Can you describe exactly what you did to fix this problem? Did you run a new wire from the ECU through the firewall or did you just patch something? Also, what did it involve work-wise?...what panels did you have to take out inside the car and what did you have to do in the engine bay (ie - remove UIM, etc)? Thanks a lot in advance, it'd be greatly appreciated

2a+RoN

I just ran a new wire from the ECU through the firewall and to the sensor. First off, remove the negative battery cable(I completely forget when i started unplugging the ECU, whoops). The ECU on these cars are fairly easy to get too, at least compared to my second gen. All you need to do is take off the scuff panel which just has two or three clips and should just pull off. Then remove the kick panel by removing the two retaining clips. You can then see the ECU. There will be three 10mm nuts holding it down. Remove the two lower ones and you only need to loosen the upper one to slide the ECU out. You can then pull out the wire harness clips in the back and find the wire to run. Then I just spliced the wire and found somewhere in the firewall to put it through. You do need to remove the manifold to be able to get good access of the sensor clip. However, you might be able to do it b/w the extension manifold and the firewall, I'm not sure if there is enough slack in the harness or not though. Took me roughly an hour to do all the work and get her back together and running.

-Aaron

2a+RoN

IgottaFC, I assume you have an FC from your name... When I rebuilt my engine in my FC I accidentally busted my air thermosensor and it actually just went into limp mode. However mine was an s4, I'm not sure what you have. I think s5's have the diagnostics so maybe the ecu reacts differently to a malfunctioning thermosensor differently.

daem0n

hey Aaron, thanks a lot for the great information...it'll be really helpful Hopefully I'll undertake the project soon enough. -Joe