L4701 Engine code P0118

[Firefighter71913]

I have a 2018 L4701 with approximately 400 hrs on it. It first threw this P0118 code, with less than a months worth of work on the machine. I looked into it and everything that I can find is that it’s related to the engine coolant temp sensor, which makes sense bc the temp gauge on the dash cluster, works sporadically. When I originally took it back in to the dealership to have it looked at, they agreed and replaced the sensor. Picked it up, brought it home and started bush hogging, only for it to throw the same exact code after about an hr of mowing. I called the shop and it took it back. They reset the computer and erased the code and couldn’t get it to duplicate the issue….bring it back home, start mowing with again and boom….there the code again. This time, I took it to a different dealership, filled them in on everything that happened with the last dealership….the also reset the code and couldn’t get it to duplicate. However, instead of telling me to come and get it, they tested a bunch of stuff and actually ended up replacing the entire computer. I bring the tractor back home and it works great for a while. Maybe a yr or so? I go out to use the tractor and it instantly throws the same code again. I call the dealership back and he tells me how to reset the code….I do this and all is good for a while….it through the code again last winter and I reset it and all was good. Fast forward to now….I go to start the tractor one day and there was the code. I reset it, tried again, code came back and now won’t go away…..I called the dealership and they told me that since the tractor is out of warranty, I’ll just have to bring it in. Even with the extensive paper trail of the same issue from the time of purchase. That brings me to my question….what are the chances of it having a bad sensor (at this point) and would I benefit from buying one, resetting the code and then replacing it before taking it back to the dealership and letting them chase rabbits for who knows how long and running up a diagnostic/labor bill?

 

[Firefighter71913]

 

[fried1765]

I have a 2018 L4701 with approximately 400 hrs on it. It first threw this P0118 code, with less than a months worth of work on the machine. I looked into it and everything that I can find is that it’s related to the engine coolant temp sensor, which makes sense bc the temp gauge on the dash cluster, works sporadically. When I originally took it back in to the dealership to have it looked at, they agreed and replaced the sensor. Picked it up, brought it home and started bush hogging, only for it to throw the same exact code after about an hr of mowing. I called the shop and it took it back. They reset the computer and erased the code and couldn’t get it to duplicate the issue….bring it back home, start mowing with again and boom….there the code again. This time, I took it to a different dealership, filled them in on everything that happened with the last dealership….the also reset the code and couldn’t get it to duplicate. However, instead of telling me to come and get it, they tested a bunch of stuff and actually ended up replacing the entire computer. I bring the tractor back home and it works great for a while. Maybe a yr or so? I go out to use the tractor and it instantly throws the same code again. I call the dealership back and he tells me how to reset the code….I do this and all is good for a while….it through the code again last winter and I reset it and all was good. Fast forward to now….I go to start the tractor one day and there was the code. I reset it, tried again, code came back and now won’t go away…..I called the dealership and they told me that since the tractor is out of warranty, I’ll just have to bring it in. Even with the extensive paper trail of the same issue from the time of purchase. That brings me to my question….what are the chances of it having a bad sensor (at this point) and would I benefit from buying one, resetting the code and then replacing it before taking it back to the dealership and letting them chase rabbits for who knows how long and running up a diagnostic/labor bill?

I would go with your replace sensor idea!

 

[GrizBota]

Nice how they kicked the problem down the road until the end of the warranty. I’m sure it wasn’t intentional (sarcasm). I’d replace the sensor. Then I’d get a $20 IR heat gun from Harbor Freight and check to see if anything is oddly hot the next time it throws the code. If not, I’d drive it.

 

[Fordtech86]

check to see if anything is oddly hot the next time it throws the code. If not, I’d drive it.

It may prevent this particular tractor from performing a DPF regen though, which will cause more issues if continued to run it as is.

edit: being the sensor has been replaced once and it’s doing same thing as original sensor I would look really closely at wiring between ect sensor and ecu (making assumptions that sensor is wired to ecu and networked to cluster, I could be wrong though)

 

[Firefighter71913]

Nice how they kicked the problem down the road until the end of the warranty. I’m sure it wasn’t intentional (sarcasm). I’d replace the sensor. Then I’d get a $20 IR heat gun from Harbor Freight and check to see if anything is oddly hot the next time it throws the code. If not, I’d drive it.

It throws the code on start up.

 

[GrizBota]

It throws the code on start up.

And is anything hot then? Does it get hot later? Can you just ignore the error code and use it?

 

[North Idaho Wolfman]

And is anything hot then? Does it get hot later? Can you just ignore the error code and use it?

You can't ignore error codes on a Emissions tractor, you'll end up having a ton of issues and a ton of costs!

 

[Firefighter71913]

And is anything hot then? Does it get hot later? Can you just ignore the error code and use it?

It’s definitely not hot on initial start up….and it’s never gotten “too hot”.

 

[lugbolt]

an fyi how sensors and ecu's work

ecu sends 5v out to the sensor through a wire. Sensor is nothing more than a variable resistance item. The resistance changed with temperature (in this case, or in other cases position of the sensor wiper, or whatver but they're mostly all variable resistance). The resistance causes that 5v to be reduced. That reduced voltage is then sent back to the ecu via another wire. ECU sees this reduced/variable voltage and makes adjustments. Some sensors also have a separate ground circuit, also a wire that runs to the ECU to sensor.

So as one could infer, there are several possibilities. These are not GM products (GM products throw a code every time you turn around and a lot of times for little reason, which may or may not have anything to do with the code's meaning they seem to be way too sensitive), so any time there is a code, it needs to be addressed. The possibilities in this case are ECU issue (corrosion was a big deal on them for a while), wiring, sensor and GROUND.

They've already put a sensor in it, and an ECU. So that mostly eliminates those issues, leaving you with a ground or wiring issue. WIring issues can be a bear to find, or they can be easy to find. It has everything to do with where the issue lies, or how adept the person doing the testing is with wiring. Wiring scares a lot of folks and it really shouldn't.

Lastly, dealer was "kicking the can down the road", but probably not purposely. It was likely that it it was working fine at the time they had it, then later on failed again. Or maybe it's a totally separate issue now. Remember there are more than one component and any one of them can be a cause for the code. One could try calling the customer service line, explain to them that it won't regenerate properly with a failing sensor or sensor circuit, which then might put you into the 5 year emissions warranty deal.

Good luck.

 

[Yooper]

Expanding a bit on lugbolt’s post (an excellent write up I might add!), 5v is not a lot of pressure to push through a a bad connection. Evidence is pointing to a connection being affected by heat or vibration. Slightly corroded, slightly loose, etc.

 

[MountainMeadows]

I'd start with cleaning the connections at the sensor + the ecu. Then clear the code and go from there. If it returns replace the sensor.

I use terminal cleaners similar to these:

https://www.amazon.com/dp/B098WLZC76/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B098WLZC76&pd_rd_w=xdVZi&content-id=amzn1.sym.0d1092dc-81bb-493f-8769-d5c802257e94&pf_rd_p=0d1092dc-81bb-493f-8769-d5c802257e94&pf_rd_r=B33DYPPARVR68YG1RTM4&pd_rd_wg=qeyB8&pd_rd_r=ec2960da-670f-46ce-8a3c-f7cf0ce2ef23&s=hi&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWwy

 

[RCW]

Following lugbolt, Yooper and MountainMeadows, I think that type of 5v ECU communication is common with automobiles too.

Doesn't take much to frig up that low voltage system.

Fordtech helped us through a kid's car a while back.

Have no clue if it's the OP's issue, but did learn it's a very finicky system.....thus all the advice is well-founded.

 

[Lug66]

This is from the LX3310 manual. The data is also the same from the B3350 manual so I figured I’d toss it out there. Using basic math you can create a temperature to resistance chart and decide if the sensor is operating within acceptable parameters. If your reference voltage isn’t approximate to 5v then you look at wiring or the control unit that’s providing the voltage. You can see how quickly the voltage drops as the temperature increases.

 

[Firefighter71913]

So I traced the wires the best that I could, all the way back to the cowl/dash cover, without taking it off (I didn’t have time to do that tonight) and none of the wire are chafed or shorted. Using my multimeter, I also checked the voltage at the harness connector and with the key on, it’s showing between 4.8-5.0 volts. I plugged everything back in, reset the code and let the tractor idle for a few minutes. The light stayed off. I shut the tractor off and went to start it again and it immediately came back on….does anyone have any other advice dead before I order a new temp sensor?

 

[Fordtech86]

does anyone have any other advice

check for proper pin fit on the connector terminals. Will need something the same size as the male pins to slide into the female terminals and make sure the is proper tension on them to make a good connection. Should slide with a bit of resistance

edit: can’t get diagram to load, but if there is any inline connectors in the wiring harness between sensor and ecu or cluster then those should be checked too

 

[cthomas]

Fordtech86 is right, check terminal tension as it is probably the most overlooked concern. Also I have used stabilant22 in some airbag connector issues(VW/Audi recall info,but works on GM too). Also check out what else is on that circuit as a short on any other sensor can pull the 5 volts down and cause an issue. Usually I find a K&N air filter that is over oiled and has the MAF sensor covered in an oily film.

 

[Firefighter71913]

Update for anyone interested: I appreciate all of the help and advice from everyone! After following all of the advice and checking everything that was recommended, I still couldn’t find any obvious issues. With the history of the same issue on the tractor, I contacted my dealerships service manager. I gave him a rundown of what was going on and he actually remembered the issues from the last time that it was in the shop. He told me that he wouldn’t charge me anything for a diagnostic check and depending what was found, we would go forward from there. Fast forward a week, to today….the service manager called me and told me that after running the diagnostic check, they determined that ECU would need to be replaced….for the second time in three years….he told me that it wouldn’t cost me anything and that they also found a small hydraulic leak that was covered under the power train warranty. While I’m glad that it isn’t costing me anything, I can’t help but Leary about some other underlying problem that’s causing the ECU to malfunction. Could this just be a freak coincidence?