thaeleelyr

I've had a minor exhaust leak, supposedly from the flex pipe, but I never saw any coming out from the length of the entire exhaust. I also had an issue when I was idling. The mechanic said it was idling at the proper RPMs, but on occasion it would seem to drop just a little bit RPM and would be rough. My fix (since my mechanic didn't care) was to keep the idle up with the gas peddle if needed. I could also smell exhaust in the cabin if standing still, but the mechanic said that was because of the minor exhaust leak (which was on the schedule to get fixed).

Recently, I made a long trip. I stopped at a store and when I restarted the engine (still warm), it seemed to lag a little when accelerating on a flat surface and I could hear the exhaust leak (or what sounded like exhaust). When I tried to get up a hill, I lost power as if the engine were being choked off and the exhaust smelled bad as if it wasn't burning properly.

I got the above trouble codes and no others, and when I look under the car, I can see the exhaust leak (a lot) at the junction right in front of the catalytic converter just under the cabin and I discovered the 3rd O2 sensor that is between the cat and muffler was lose, letting out some exhaust. I'm planning on replacing the seal that goes between the pipes, but what I am wondering is, would this large of an exhaust leak throw off these trouble codes?

Someone mentioned a plugged up cat, but there is plenty of exhaust existing the tailpipe. Could there be another problem that isn't being registered by the trouble codes? Could my cat be plugged up as well? Do I really need two new sensors or do these refer only to bank 2? I'm a little confused on that because I thought they registered both banks, but then I read a thread stating that they involved just the one.

I would just like to get a handle on what I am dealing with before I take it to the lazy genius or I may simply fix it myself.

Thanks for all replies.

Baetke

P1135 and P1155 are A/F sensor heater circuit malfunctions. Since it is unlikely that both of them failed at the same time, check the components common to both heaters; the A/F heater relay and the A/F heater fuse. Once the A/F heaters are working again the P0171 should disappear as well.

Please fix the exhaust leaks ASAP. Wouldn't want anyone in the vehicle to get CO poisoning.

thaeleelyr

Thanks for the reply. That makes me feel better because I thought both going at the same exact time was odd, but the mechanic was swearing it wasn't. I think I found the thread on checking those and they were on the list of things to do.

I started him up yesterday to check for air leaks and I think I heard a hissing sound coming from right behind the air filter housing. I didn't see any broken hoses, but I haven't taken the housing off yet as it was 20 degrees and my fingers were frozen by the time I got to that point. The only other thing I wanted to check was the PCV, but I haven't found a thread yet that explicitly states where it is. I think I checked it before following some instructions, but I've lost those. I know this makes me an auto moron, but can you tell me where that is located?

Thanks again!

Baetke

Here is a photo showing the pcv valve location. It's the little black elbo just below the silver can.

thaeleelyr

Thanks for the PCV pic. I checked the fuse and the relay switch (I think this was from another thread) and both were good. I pulled the front sensor (bank 1) out of its harness and put an ohm meter on it. I didn't get any reading, which I assume means it has a short. However, it's pretty cold here and the manual I have states that it should be reading between 0.8 - 1.4 ohms at 60F. Should I try to remove the whole thing and then re-test at a more normal temperature or do you thing it is blown? Also, is there a way to access the bank 2 sensor electrical harness without crawling underneath the car?

Thanks.

Baetke

If by "didn't get any reading" you mean the ohmeter didn't display a number, just like if you don't touch the leads to anything, then your A/F heater is blown. This is an "open" circuit, not a "short". A normal reading of 0.8 to 1.4 ohms is pretty close to a short circuit and is normal for a cold heater. As they warm up their resistance increases but you won't be able to measure this except by measuring the current and then doing some calculations. Anyway, sounds like the Bank 2 A/F heater is bad. Do the same test on the Bank 1 A/F sensor and if you get the same results I think you've found your problem. There have been threads on disconnecting the rear A/F sensor but I seem to recall it may be easiest with two people. One from the bottom and one from the top so you can each pull one half of the connector. Good luck, and keep us posted on your progress.

Baetke

thaeleelyr

Ah, so what is the difference between a "short" and "open" as far as circuits are concerned. What reading would indicate a short? Just curious and I'd like to get this straight in my noggin.

One thing I noticed in the manual was the range for the ohms was listed as you said, but taken at 60F. Would 20F weather affect the reading? Would it be better to get the sensor warmed up a bit and re-testing?

Thanks!

Baetke

A "short" refers to something connected to your circuit that shouldn't be. For example, if the insulation on a wire chafed through allowing the wire to touch the chassis, you would refer to that as a "short to ground". This is the most common type of short circuit in cars but you can also have two wires short to each other.

An "open" circuit means a wire or component is not connected when it should be. If a wire broke or was cut, that would be an open circuit.

Where it gets more interesting is when you have something in-between and this applies to your heater measurement. Heaters have a very low resistance when they are cold. Your meter will measure a value very close to, but not quite, zero which is also what you would interpret as a short. This is perfectly normal for heaters and light bulb fillaments. Their resistance rises rapidly as they warm up but you can't measure that directly, nor do you need to. All you really need to verify is that you have continuity ( or a short ). This tells you that the fillament or heater is not burned out. If it was, you would measure infinite ohms or an open circuit and you would know the part was bad.

Hope that answers your questions.
Baetke

salimshah

^ Very nicely explained Baetke!

When we are talking 1-2 ohms, you ohm-meter must be capable of making that measurement (would require some means of zeroing the meter when you short the probes)

Salim

thaeleelyr

Thank you so much for explaining that!

I've gone ahead and changed out the sensors and now the codes are gone, so they were definitely broken. I really appreciate your help.

Baetke

Glad to help. That's why we're here, to help each other out.