Need Your Help Please - CEL P0115

[jnettrecker]

Note: I have used the Google search and did not come up with anything helpful so if you would share your wisdom, I would be very grateful.

I have a 1997 Toyota 4Runner Limited, 4x4 Automatic 3400 v6 w/ 226,000 miles that has thrown a P0115 code, after pulling the breather apart and plugs out to do a compression test (I also pulled timing belt cover to inspect and replaced the thermostat at the same time). Code will not clear. Instantly comes back up on the programmer after you clear it. I'm guessing it coming on after that work is just a coincidence though, since 3 days before this I replaced the front (engine side) O2 sensor. The original O2 sensor bolts are completely rounded off, so I ended up using a spark plug fowler, cut the end off, drilled a hole in the pipe and welded it in parallel to the ground, giving me a place to screw in an 02 Sensor from another Toyota 3.4. I think it was from a T100. I bought it at O'Reilly and it's a Bosch.

My question is this; Can this code be triggered by the O2 sensor? If so, and I need to get an OEM or Denso sensor can someone give me a part number of one that will screw in so I can use my setup? Short of replacing that section of exhaust, that old sensor isn't coming out. If it isn't the O2 sensor, any other ideas?

Thanks,

Josh Brown

 

[TheDurk]

OK. Let's try this again. No, I would not expect this to be thrown by the O2. P0125, which also relates to the ECT CAN be thrown by the O2. But P0115 is a circuit failure--open or short--and this condition is the wiring or the sensor. At least as far as I know.

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0115.pdf

But I'd ditch the Bosch anyway. The rear sensors off the '01-'02 V6 3.4l's are screw-in. The plug is different, and the wire length is probably wrong, so you might as well get the universal type Denso 234-4209:

This goes for $30 on Amazon, Prime eligible. I'm not positive it has the same characteristics as the earlier flange types, but I would bet that it does. And if you are going to do it anyway, do it first, and then we will know if I'm right. I just don't see how an O2 sensor can make the ECM think there is an open or short on the ECT. Although, the ideal would be to hook up a live scanner that can read the coolant temp output; if the temp is locked at max or min, you definitely have a problem there. And that doesn't cost anything if you have the scanner.

http://www.amazon.com/Denso-234-4209-Oxygen-Sensor/dp/B000C5WCUE/ref=sr_1_1?ie=UTF8&qid=1375905302&sr=8-1&keywords=2344209

 

[the great him]

dump your bosch o2 sensor and get a denso one i will bet money the issue will go away

 

[jnettrecker]

Denso O2 sensor on the way. Thanks for the link.

I only have an OBD II reader. It isn't a scanner you can plug into the troubleshooting port. Where is the sensor that the P0115 is related to and is it a part that randomly goes out? I don't know what wires to check, It just seems strange to me that it would all of a sudden throw that code right when I had just done all that work......

 

[jnettrecker]

Btw, that

Web hosting, domain names, VPS - 000webhost.com

doesn't work for me.

 

[TheDurk]

Btw, that doesn't work for me.

Is that my link? It looks fine from here, it's to the FSM for P0115 at the Tacoma file site. But that's not what you posted. You may have some filter that blocks it. Can someone else try it, please? I post these all the time.

 

[jnettrecker]

Yes. That was your link. Wouldn't open for me. Said bad response??? I'll try again when I am back on my Mac.

 

[the great him]

works for me

 

[jnettrecker]

tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0115.pdf


Technical description:
502 Bad Gateway - Response Error, a bad response was received from another proxy server or the destination origin server.

 

[TheDurk]

tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0115.pdf


Technical description:
502 Bad Gateway - Response Error, a bad response was received from another proxy server or the destination origin server.

Well, idk. Worked for The Kid. Try adding http:// before tacoma--that should be there, but even without it, it works for me.

If not, ditch the Mac and get a PC. (You do have Adobe Reader on that thing, right?)

 

[jnettrecker]

Ha. Love my mac. http:// did the trick. "Where" is the Engine Coolant Temp sensor is located?

 

[jnettrecker]

Please pardon any errors. Siri is typing this for me while I am driving.

Is the ECT the same sending unit that controls the temp gauge & screws into the block under the fuel rail on the front, top passenger side of motor? Just trying to figure out where it is because of the paragraph below.

I was doing some more troubleshooting last night and I pulled the timing belt cover back off. When I had done the thermostat and inspected the timing belt etc. I had sprayed off the antifreeze on the front of the motor with a hose. This was at the same time I did the compression test and also the exact time the P0115 code came on. There are two wires that come out of the engine underneath where the coolant hose exit (Center, Front, Top) on the motor. They had a very poor heat shield insulation on them and it looked like there was some moisture down in the "deep abyss of no return" that they go into. So I blew wverything out real good & put new heat shrink tubing on them the best I could. It isn't a job that I am very proud of, but it's better than it was. Here is the interesting part, after I got done I got back in the truck cleared the codes and the code cleared (it hasn't been clearing out at all, just comes right back). Started it up and truck ran normal for about 2 min then code came back and won't clear again.

In this same work phase I also swapped the plugs on my O2 sensor back to the old one (the one permanently fused to exhaust). I tried switching back and fourth between sensors and it didn't seem to make a difference. However leaving the sensor unplugged did throw another code (don't remember the number).

One other note worthy thing. When I put the timing belt cover back on it was nearing midnight & in my sleepy stupor I managed to get the wire for cyl #4 caught behind the cover and nicely pinched it nearly in two making a beautiful mis-fire on Cyl #4. This also happened at the same time the P0115 momentarily cleared.

Honestly I don't want to but I'm about ready to give up and take it to a mechanic. It's just maddening, lol. Here is a pic, just someone tell me it's worth it

 

[TheDurk]

That is your ECT sensor, that feeds the ECM and is what the code is about, although I think the temp gauge has a different sending unit. It does on my BMW.

But yeah, this tends to confirm the P0115 is a wiring issue on the ECT as I said before and not the Bosch o2 sensor. Honestly, if you can't get your hands on a live scanner that reports the engine temp, this will be hard to troubleshoot. If you have an Android phone or tablet, a Bluetooth adapter and the Torque Pro app will cost you about $35 and work on any car since 1996. Well worth it. But you probably have an iPhone if you have a Mac.

I certainly wouldn't ditch the truck for this. The next guy will be laughing at you.

 

[jnettrecker]

Just wanted to post a follow up so anyone else who ever has this issue knows my resolution.

1. The 2 wires coming out from under the intake below the coolant exit port on the front center of engine go to the knock sensors and have nothing to do with the code, I guess it was a fluke that wiggling them let the code clear.

2. The single wire sensor the diagram shows underneath the intake manifold is the one that sends a signal to your gauge. It has nothing to do with the computer and will not throw a code, ever.

3. The Bosch O2 sensor was working properly. I did replace it with the new Denso but the P0155 code still remained. I'm not saying Bosch will work or will work long term, I'm just saying this one was working properly and was not the cause of the code.

4. The ECT or Engine Coolant Temperature sensor is the 2 wire sending unit that is on the front passenger side of the motor just underneath the fuel rail bridge. This sensor sends a signal to the computer telling it what temp your motor is running and along with the O2 sensors, helps calculate the fuel air ratios etc. Sometimes we create our own issues........ During my search for the overheating issues (Overheating Challenges) I had replaced the sensor with one from O'Reilly. BAD BAD BAD idea. The guys at OReilly aren't bad, but there are several things you should NOT buy from there, (I have learned). I was at my wits end and since I was making the long drive to the dealership anyway, I decided to buy a new OEM ECT sensor and try it (since that what the code was for after-all). Screwed it in, cleared the codes and wala, problem solved. That stupid part had me ready to sell the truck! Put around 4 hours on the road today and it runs like a champ. Seemed like that fuel gauge didn't move quite as fast either, since my motor wasn't chugging like a freight train, lol.

 

[xddanx]

I am in the same boat, I had a p0115 error. I replaced the ECT with Standard Motor Products TX40 Temperature sensor. Cleared the code and it came back. Whats my next step?

 

[cruisercorner]

I am in the same boat, I had a p0115 error. I replaced the ECT with Standard Motor Products TX40 Temperature sensor. Cleared the code and it came back. Whats my next step?

seems like it would be to replace with an OEM or equivalent, instead of a cheap rock auto ECT.... but it's been 6 years since you posted, so I guess you figured it out.

I also have a P0115, going to try dropping in an OEM replacement - it's only about $40 shipped. I'm having rough idle at start up... hopefully this will solve my CEL, and maybe help my rough idle too...

 

[Dnorman]

seems like it would be to replace with an OEM or equivalent, instead of a cheap rock auto ECT.... but it's been 6 years since you posted, so I guess you figured it out.

I also have a P0115, going to try dropping in an OEM replacement - it's only about $40 shipped. I'm having rough idle at start up... hopefully this will solve my CEL, and maybe help my rough idle too...

Did that solve your issue? Currently experiencing a p0115 also

 

[One Sick Puppy]

Just fixed my P0115 error. My truck was very hard to start this morning; but basically a no-start situation. Starter and electricity seemed strong, tho, but wouldn't fire up. CEL was P0115. Did some searching and found this thread. When I went to find and examine the ECT sensor, low and behold one of the wires was broke.

The pigtail on my ECT sensor at the front, top of the engine had a broken wire at the harness connector. I was able to halfassedly solder the wire back together and then I used some Shoe-Goo to seal and reinforce it. I'm not expecting it to last too long, but I was quite happy to have less than 24hrs downtime and should be able to drive to work tomorrow.

Aiming to do a better fix/replace sooner than later. Looks like the sensor might be perfectly fine and this might last longer than it should, but should be good for now. Hopefully this helps others in a pinch. Sorry, I didn't get a photo of the before situation, but you can imagine that soldering wire being broken at the connector with about 1mm of questionable wire accessible. I wasn't expecting to be able to get any solder to stick but I lucked out. Then lucked out even further being able to get the loose wire to stick to it.