Check engine light (1 Viewer)

[Josh83]

Well, I've owned it for 3 days and got the P0401 code, but I also have a P0116. Autozone told me this is "Engine Coolant Temp". First, I know my coolant is s*** and needs changing and that was on my list for this weekend. But in my searching about the P0401 I found some references to the "temp sensor". Could these two codes be related? The autozone guy told me the coolant temp code ment the coolant temp sensor was bad, but I'm not so sure. What do you guys think?

 

[MrZumma]

Josh,

Do a search for P0401. You will find there is some good information on this board to help resolve this issue. Here is a good P0401 link to get you started.

According to the FSM (You are planning on purchasing one, right?), first check the thermostate to verify that it is working properly. If it is working properly, then replace the engine coolant temperature sensor. Basically that is it..

Check with CDan on purchasing the FSM for your '97. Well worth the expense...

 

[Josh83]

I think I am fairly clear on my plan of attack for the P0401, I was just curious if anyone thought that the other code could be causeing the P0401. I will test the thermostat when I flush my cooling system this weekend.

EDIT: I am planning on an FSM and EWD, I just need to get a paycheck this weekend first

 

[Scamper]

Gumby started a thread on the ECT and EGR a while ago. Here 'tiz:

https://forum.ih8mud.com/showthread.php?t=17600&highlight=EGR+temp+sender

The ECT does in fact influence the EGR, though I'm not sure it would result in your P0401 and P0116 combo.

 

[Beowulf]

Josh,

As far as I know the EGR temp sensor has never been identified as a cause for the P0401; at least it has never been reported here on IH8MUD or other forums that I've followed. The EGR temp sensor has nothing whatsoever to do with engine coolant temperature.

I believe those two codes are unrelated.

Resolving the P0401 has been discussed at length. I'm certain you will obtain more information than you care to digest by doing a search for "P0401" in the 80 section.

In regard to the P0116 code, this points to a malfunction in the engine coolant temp sensor. OBD-II computers are pretty smart. "If a coolant temp sensor reads 200 degrees F one minute and drops to –30 the next, the ECM will realize something is wrong and remove its output from the fuel and spark decision tree. (In this case, the ECM will base its decisions on a coolant temp of 176 degrees F.)" If you will advnanced search for Author=Rich, Keyword=sensor, in the 80 section you will get some pics of the sensors and their locations. There are 2 engine coolant temp sensors, one for the gauge and one for OBD-II. Some of us have installed a third for a *real* gauge but that's for another discussion.

-B-

 

[sassyav8r]

Happy Thanksgiving to all-
I bought my '96 FJ80 back in '98 and have loved it ever since. (85K miles) 2 days ago the infamous
Check Engine Light came on for the first time . I will be doing the Auto Zone check tomorrow. What concerns me is that 5 days ago I bought gas at a different station. Not long after, my 80 ran rough, especially when it was in reverse or just above idle. After acceleration, and many days on this tank, it has finally smoothed out.
Main question is could bad fuel be one of the reasons for this light to come on? Assuming the code will be PO401.

Thanks for all the info. everyone shares.

Sas

 

[landtank]

doubt it, if it's the gas I'd expect a O2 bank sensor or similar.

 

[Beowulf]

>> Assuming the code will be PO401. <<

If it is a P0401 then the gas had nothing to do with the code. If it was running bad you could have one of the P030x codes where x=cylinder misfiring. I suppose bad gas could cause this but it would have to be some really bad gas and your fuel filter is probably clogged. Throw in a bottle of Red Line or BK44 fuel treatment at the next fill-up.

-B-

 

[semlin]

the primevil OBD 1 on the prehistoric 91 can also detect a bad ECT B-Wulf but it unfortunately does not remove its input from the decision tree with pretty disastrous results.

I think you will find those codes are unrelated. When fixing the ECT you should definitely replace the t-stat at the same time as you do this and you should also take the opportunity to do a full rad flush (check past threads here for details). You could try replacing the thermostat, flushing the rad and block and carefully removing and cleaning the temp sensors before you replace the temp sensor but that didn't work for me and meant I had to use more Toyota red coolant to half empty the rad again to get the tewmp sensor.

I would also check the hoses around the temp sensor. In my case the source of the problem was a small hose leak onto the sensor which caused the sensor to deteriorate.

Oh and if you are really keen take the time to do your PHH as well!

 

[reffug]

BK44
-B-

BG44K fixed it for you -B-

 

[Beowulf]

BG44K fixed it for you -B-

If that's a question then the answer is no. I wasn't proposing BG44K for the P0401; it's for cleaning the fuel system and may help if he got bad petrol.

-B-

 

[reffug]

If that's a question then the answer is no. I wasn't proposing BG44K for the P0401; it's for cleaning the fuel system and may help if he got bad petrol.

-B-

No question just correction. Never heard of BK44.............

I get jokes............