2ks

Originally had a code for the fwd air fuel sensor (o2 sensor) I replaced both fwd and aft (bnk 1 and 2) sensors with same p/n of sensor. Fwd sensor code went away with no problems, but the aft sensor codes p1135 and p1155 came on even though it has a new sensor in it. First thing i thought was a bad from mfg sensor so i put a known good sensor (in this case the fwd sensor with no code) in the aft spot. Still throwing the codes. YES i have reset them both with my code scanner and even tried disconnecting the battery for 1/2 hour. Codes still come back after about 30 seconds after start. I have trouble shot the system a bit, thinking maybe a relay in the system has gone bad or something. Made jumper wires and with an assistant took readings at all of the 4 pins at the connectors (jumper wires installed between vehicle connector and sensor connector. All readings match the known good sensor (fwd one) I KNOW it is not the sensor or it would throw the code when i put it in the fwd spot. Any one else had this issue? ANY help would be appreciated!!! Dealer wanted $700 to replace both sensors ($200 per sensor is part) and since i thought that was absurd i ordered after market sensors for about $50 each. Took only 1 hr to change both of them but have been fighting the Check Engine/ VSC/Trac off codes ever since. Thanks Kevin, Savannah, GA.

carguy07

Get real Denso sensors or you will be chasing your tail on this one. These cars are real pissy when it comes to aftermarket sensors.

artbuc

You can not get the right A/F sensor for $50. You will have to pay $90 or so for the correct Denso.

EDIT: Inflation got me. Looks like the current best price for 234-9009 is $92 plus S&H.

hypervish

X3, you MUST use Denso sensors. The ECU doesn't play nicely with aftermarket sensors.

2ks

Ok got it about the denso sensors so someone explain to me why an aftermarket works fine in the fwd position, either aftermarket sensor i use works fine. But the aft is giving me grief???????. I will look into the Denso, but the original may still be good if this is the case. After all i didn't have a aft sensor code until i changed both sensors at the same time.

carguy07

I doubt you will make any sense of it. It falls under that "pissy" thing. Someone else could use the same aftermarket sensors and they might not throw codes for them.

All I can tell you is these work like a charm everytime: http://www.amazon.com/gp/product/B00...00_i00_details

2ks

Thanks for the link, the next painful thing was to take it to the Stealership. I am going to try the denso and then go from there. I have a Bosch for the O2 after the cat conv. Should i not use it when i have a problem, i ain't messing with it until it codes, cause i need to remove the effing back seat to get to the connector. Just don't know if it acts differently than the A/F sensors, will i be going down this road again? I will give to my friend who has a Highlander but it is the same engine so may not do them any good either.

carguy07

I don't think the one after the cat is nearly as sensitive as the front ones. It would likely work fine. IMO

2ks

Ok now have a Denso sensor in there, brand new. Still throwing a P1155 code. Anybody got anything? I am at a loss here. Just about to go to the Dealership and smack the nearest salesman.

P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

rxtaylor

Hi 2ks.
Did you get any resolution to this?
I just ran across a similar problem in my '02 rx300.
Started with a P1135 code. Checked the Valve Vacuum Switch behind the air filter (This had been the problem once before, and it had indeed once again been popped out from the last oil change - going to have to put a sign on that air filter for the lube technicians asking they not check that thing). Tried to clear the code and it came back.

So I decided maybe somehow the lube techs damaged the internals on that switch and decided to replace it. Last time this was the problem, the housing on that switch had been cracked so replacing that switch actually worked. I cleared the P1135code... and it came back.

Gave up and decided to actually change the upstream O2 sensor, though I had no reason to suspect it other than the code number. Mistakenly changed the wrong upstream O2 sensor (the one easy to get to on the front of the engine). Cleared code... unsurprisingly P1135 returned. Put that old O2 sensor back in, and cleared the code just to be sure. Yep. P1135 returned.

Figured since the code was still there, the Valve Vacuum Switch really wasn't to blame after all, and I put the old switch back in. Cleared the codes... yep P1135 returned. (I should add at this point, every time I replace a sensor, I first disconnect the negative so it's off for like a half an hour, then I restart the car, make sure the code comes back on, then clear it with the code-reader, and it comes back again).

Finally, I switched out other upstream O2 sensor with the new one. (This is the sensor closest to the firewall on the backside of the engine still upstream of the cat.

Restarted the car... NO P1135.... Instead, I get P1155!!! Just had to laugh. Saw you've been struggling with P1155 yourself. Any news?

code58

RX- a little tough to follow since you don't identify sensors by their position (IE: B1S1& B2S1), rather upstream here or there. IF I follow the sequence correctly concerning what switching you've done, it indicates that the sensor that you are currently showing in B2S1 position (what you indicated is the NEW sensor) is BAD! Please understand that you can't switch parts around like a juggler and expect it to magically be fixed. From the very beginning, the code you got (P1135) indicates ONE thing and ONLY ONE!. That is a bad heater in the rear sensor. That code is very specific to only one thing and shouldn't ever have anything to do with the hose being off the air box or any other problem.
What brand of sensor (AND part# please) did you use? Often other brands of A/F ratio sensors don't work well with Lexus, therefore I would never use ANY brand but Denso. We'll try and help you, but you got to come down to earth a little bit to recieve that help.

code58

Kevin, like RX (last poster in this thread), your story is hard to follow. You really need a better understanding of what the codes you are getting mean and what triggers certain CEL's. I do say, FOLLOW the advice of the others who have said GET RID OF THE AFTERMARKET SENSORS! If you decide to use good used sensors, for goodness sake make sure they're DENSO! (I am not suggesting used sensors!)
You say "the aft sensors code P1135 & P1155 came on". Do you realize you posted the codes for BOTH sensors, NOT for just the rear sensor. Those 2 codes are SPECIFIC for the HEATERS in both front and rear (B1S1 & B2S1) I should add right here that MOST Lexus DTC lists have an ERROR at this point, and it causes a lot of confusion. I suspicion this error came straight from T/L. I have sent a correction from their site to one of the major DTC code suppliers (one I use all the time and respect) almost a year ago and there never was a correction. The error is showing the explanation for P1155 as B1S1 and it is clearly supposed to be B2S1.
Please don't say you know it's NOT the sensor if you have aftermarket sensors in there. I also don't know where, outside of alley in Tialand, you could buy even aftermarket sensors (supposedly correct ones) for $50. apiece. A lot of the name brand aftermarket A/F ratio sensors are MORE expensive even than the Denso sensors, now that the Denso's have come down, even though the aftermarkets OFTEN are problematic and sometimes don't even work right out of the box. (Not terribly uncommon for them to throw codes when brand new, even though the only problem is the aftermarket sensor. If you feel like chasing your tail people, buy aftermarket sensors!
Please also realize that there are a TON of things that will trigger THOSE 3 things together (CEL, VSC, &TRAC off lights) that doesn't necessarily point to anything other than "Hey, something needs your attention!" Probably 15 or 20 different things that can trigger that combination.

code58

Kevin, note my correction to this code!!! (Is actually B2S1)

rxtaylor

Hi Code58,
Thanks for taking an interest.

Started with code 1135 (Bank 1 sensor 1).
I screwed up, and replaced (Bank 2 sensor 1) with a DENSO sensor instead. Stupid move on my part for sure and I freely admit it.

By the way, you're right, locally here, DENSOs are same prices as the Bosch, so why wouldn't you use them?

When the code didn't go away, I checked and realized what I had done. So I put the original sensor back into the Bank 1 Sensor 1 position and checked the codes again. (I wanted to make sure I hadn't damaged the original sensor in the process of removing and putting it back in). Still only got the 1135 code. So I went ahead and put the newly purchased Denso into the correct (Bank 1 sensor 1) position.

Now the 1135 code is gone, but I get an 1155 code (which is my understanding really is Bank 2 sensor 1 (Even though (as you're right again) several of the OBDII code sites have it listed wrong a number of different ways).

Nothing I've ever read, or understand about these things, suggests to me that I should HAVE to replace, BOTH Bank1 Sensor 1 and Bank 2 Sensor 1 at the same time, but it looks like I'm going to wind up doing so. Just hoping it's not a deeper (ECM) problem.

That's why I originally asked Kevin how it worked out for him in the end.

fd3sboost

just going thru same problem, i replaced the two front a/f sensors about 2 years ago with lexus parts, now this week i get p1135/ p1155 codes and i just replace them again with the denso sensors and after a few miles codes came back again.