xander79

I have changed the O2 closest to the firewall and cleaned the MAF sensor, granted those were for other codes 200 miles ago. I have had the codes cleared to see if they come back, nothing yet but I have only driven 20 miles, maybe. What should I look for if they come back? One problem or multiple problems?

Lexmex

Welcome to the Club.

I'd take a wait and see approach, but that P0330 would give me issues given it is a knock sensor, which is not the easiest thing in the world to get at.

xander79

If I have to change the knock sensors I will probably just do a rebuild, the engine is at 141K. I just bought it 600 miles ago; I received a good price so I can't complain.

xander79

Oh... I have read up on the knock sensors and I have noticed that people are losing overdrive. I still have OD. And its getting 15 city and 19 Hwy.

Lexmex

Do you run E10 gas out there?

xander79

Not that I know of. I see that grade in the rural areas though. I do only use 87 octaine, should I use higher?

Lexmex

I would. When I lived in Mexico City, my uncle and I wouldn't see too many, in part because running the lower octane at higher altitude was favorable (despite the other issues with the gas down there), but guys would come to either nationals at Hermanos Rodriguez or even to my own 1/4 mile track from lower elevations would report knock sensor issues from 87 octane use in things other than a 4 cylinder vehicle.

xander79

I will switch at next fill, and put some 91 and Lucas aditive in, and see if a get the codes back... TBC

xander79

Ok... I have filled up with premium a few times and cleared the codes several times and they are still coming back. I have noticed some gas mileage issues, about 2-3 MPG off from what is should be. The RX itself seems to be running fine; I even was able to see a difference after I switched to premium. What should my first item to look at? I am leaning toward the AF Sensor. Not only is it giving me a P1155 it is also giving me a pending P1155, along with the P0125 and P0330. Just to double check that is the one closest to the radiator? I believe the knock sensor code is false, since the car is running fine, but we will see. Any help would be appreciated.

xander79

Should I clean the MAF sensor again? Or replace it all together?

Lexmex

That's knock sensor 2, is closest to the front of the vehicle, but best to replace both since it is a pain to get at. If you pull the battery to clear the codes, and still that P0330 is coming up, best not to treat it as false, as a bad knock sensor can trigger A/F codes as well, the knock sensor is the one to focus your attention on. It's not generally one that shows up for a temporary bad sensor reading, but because the knock sensor really is bad.

You can also have a mechanic read the A/F sensor readings to see if something is wrong apart, but the knock sensor is the one I'd focus on. The p1155 is related to the a/f sensor on the front by the radiator.

xander79

What are some of the other items I should change while fixing this? Plugs? Timing Belt? My RX has 142000 on it and I dont know what service has been done: I only bought it a month ago...

Lexmex

You really need to have the dealer run a check with your vin number to see what service has been done. As far as what the previous owner(s) did independently, there is no real way of knowing. You are at about a middle point as far as a second timing belt change (still a bit aways) and that also goes for the plugs. My main concern would of course be engine oil having been changed and even more so for the transmission fluid.

OldSalt

Overdrive goes out due to the car being in self-protective "limp-mode" when certain trouble codes are seen. I see it go out intermittently when I ignore problem codes. Right now I have three problem codes, which seems unlikely. The are two O2 sensors and 1 knock sensor. This can be caused by bad sensors, by bad harness, or by a bad ECU, says the troubleshooting manual.