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P1173 Code Air/Fuel Mixture

I have a 95 Mazda Millenia with 218K miles (2.5L) non-supercharged.

I got a P1173 Feedback A/F Mixture Control (H02S21) code. Please help.

I reading on what fixes this currently and having a hard time finding a fix specificaly to the Millenia.

I have recently replaced alot of vacuum solinoids because they were bad. Plus a alot of other work to the car. The car was doing fine for the past few days and now this code.

I have not rest it and see if it comes back or not.

Not Familiar with this engine, however I did find all of this on the web:

P1170 - Feedback A/F mixture control (ho2s11)
P1173 - Feedback A/F mixture control (ho2s21)
Break down the code as follows:
"Ho2s" for Oxygen Sensor. The numbers after the "s" refer to locations. In the case of 11, its bank 1 circuit 1. Where as the 21 would refer to bank 2, circuit 1.
example, "ho2s11" we could say: oxygen sensor, bank 1, circuit 1

must be an engineer's answer. all kinds of facts, but it dont make sense. the reason you have those codes is simple. you have air leaks in the vacuum line system, most common is broke plastic "tee's". depending on which engine-2.5 or 2.3, the job can be difficult, or pain in the butt(2.3). parts are really cheap, but labor will break your wallet

Check your electrical connectors as well. (My opinion).

I am assuming the bank 2 circuit 1 is the top o2 sensor next to radiator. Is this correct anyone?

I have not owned this car long so its all new. I noticed the car idles at about 1300 with ac off and 900 with ac on. This is strange to me. Is this normal? Also when in drive or gear its 900 rpm at idle.

I have checked all the vacuum lines and all are good. Its pulling 21" at the 1300 idle and 16" at 900 rpm. This seems good to me.

dumb answer. if the there was a broke tee, it would throw a p0170/0173. while 1173 is a code for heated oxygen sensor, bank 2(lh), the fsm has a much better explanation than something googled on the web. i dont have a 2.5, but i do have the fsm, and i can read. also, 16" at 900 is a bit low, but if there was a broke tee, it would be more like 8". there are several things to look at on this engine. ign distributor is one. check on the probe or mx6 forums, since they have the same engine. also, the idle control valve could be bad, and then i see a lot of posts where people mess with the air screw on the mas. this is a real no no. the ecu tries to control idle with the help of the icv. however, if timing is off, which can be caused by a faulty ign distributor, since they are mechanical, you can get a funky idle. then i see posts were desperate owners will change the tps. generally, it goes downhill from there. also, lots remove the throttle body to clean it, and do not seal it well after reinstall, but here again, i think you would get air leak codes 0170/0173 if this was the case.

Thanks for the input.

I have gone over these vacuum lines 20 times and with a manual also. I know its not a vacuum leak. The only thing im not sure of is there is large vacuum lines which come right aft of the throttle plate/body and split to 3. One of the 3 goes to a small looking white filter mounted on the firewall. When i bought the car the other end of this filter (I call it) is to open air. I can find it in the manual or anywhere. Im assuming its supposs to be sucking air.

This idle issue. I have checked the idle control valve per the manual and it states if you disconnect the connector the idle should drop. It does. So I assumed this vavle is ok.

I checked the top O2 sensor next to the radiator yesterday. We will see.

I am only trying to get this car ok for someone to by. I cant sell someone a lemon. I bought it and it had a load of problems and karma is a bitch.

Quote:

Originally Posted by TIM219 (Post 129493)

The only thing im not sure of is there is large vacuum lines which come right aft of the throttle plate/body and split to 3. One of the 3 goes to a small looking white filter mounted on the firewall. When i bought the car the other end of this filter (I call it) is to open air. I can find it in the manual or anywhere. Im assuming its supposs to be sucking air.

Acts just like a vaccuum leak to me, however I don't know this engine set-up. Is there at least some kind of valve control in the line?
I had a vaccuum leak internally from the brake booster in my Mazda 6 that caused me nothing but problems and was not easily detected. The only way it was detected was by pinching off the line and watching the scanner and characteristics of it.
Try pinching off that line.