tangocash
Posts: 24
Joined: Sat Aug 25, 2018 11:51 am
Location: Los Angeles CA.

Re: Replacing REX fuel temp/pressure sensor

gta3005 wrote: Mon Sep 19, 2022 1:43 pm Any updates on these issues? I've got the same two codes, p0480 and p14fa ( thanks for providing what this one is!). I replaced the front fan behind the radiator this weekend because that's what BMW recommended but I still have a historic p0480 fault. Going to try running the rex to get it to go away.
I haven't had a chance to go in and look yet, but my first order of business was going to be a part-by-part inspection along the system to find any visual signs of loose connections and wear that may pinpoint what part is the obvious problem. Replacing the fan sounds like a good start, but now that you've swapped it out, perhaps it's a bad sensor along the path?

Does this mean replacing the fan fixed your P14fa error code, but not the P0480? I've been trying to locate the exhaust temp sensor in the car to see if its a cost effective attempt to fix P14fa.

I need to get my hands on a legit PDF of the service manual so I can better navigate these issues but I haven't yet decided where I'd trust to spend the money.
2014 BMW i3 REX
agzand
Posts: 113
Joined: Tue Dec 22, 2020 3:00 pm

Re: Replacing REX fuel temp/pressure sensor

https://attachments.priuschat.com/attac ... Engine.pdf

I think it is item 5 on page 37 (monitoring sensor), but I am not sure.
gta3005
Posts: 4
Joined: Thu Feb 07, 2019 5:23 am

Re: Replacing REX fuel temp/pressure sensor

Interesting PDF, thanks for adding that.

It did not get rid of the P14FA code. I've had that code for a long time and it tends to be intermittent so I haven't been focusing on it. I need to fic the P0480 before the end of month for inspection, so we're gonna find a solution to this!!

I have been meaning to check F72 – 5A – radiator fan relay (https://fuseandrelay.com/bmw/i3.html). I figure if the motor was shot (which it didn't seem to be in horrible condition, just minor resistance compared to the new one) then it could have fried the fuse as the vehicle was trying to run it.

I took a lot of pictures of the fan swap with the intention of creating a DIY. It's not a horrible job, took me probably 6 hours. But, if I had known exactly what I was doing from the beginning, probably would have only taken 2 or 3 hours.
tangocash
Posts: 24
Joined: Sat Aug 25, 2018 11:51 am
Location: Los Angeles CA.

Re: Replacing REX fuel temp/pressure sensor

agzand wrote: Mon Sep 19, 2022 11:53 pm https://attachments.priuschat.com/attac ... Engine.pdf

I think it is item 5 on page 37 (monitoring sensor), but I am not sure.
Great document, thanks! That looks exactly like the part I've been Googling.
2014 BMW i3 REX
tangocash
Posts: 24
Joined: Sat Aug 25, 2018 11:51 am
Location: Los Angeles CA.

Re: Replacing REX fuel temp/pressure sensor

gta3005 wrote: Tue Sep 20, 2022 5:22 am Interesting PDF, thanks for adding that.

It did not get rid of the P14FA code. I've had that code for a long time and it tends to be intermittent so I haven't been focusing on it. I need to fic the P0480 before the end of month for inspection, so we're gonna find a solution to this!!

I have been meaning to check F72 – 5A – radiator fan relay (https://fuseandrelay.com/bmw/i3.html). I figure if the motor was shot (which it didn't seem to be in horrible condition, just minor resistance compared to the new one) then it could have fried the fuse as the vehicle was trying to run it.

I took a lot of pictures of the fan swap with the intention of creating a DIY. It's not a horrible job, took me probably 6 hours. But, if I had known exactly what I was doing from the beginning, probably would have only taken 2 or 3 hours.
I too have had the P14FA code come and go for years and, I think you're right, it tends not to trip the engine light. However, the replacement sensor that could potentially clear it is about $40 on eBay so that's an option.

Thanks for the diagram on fuses! I just checked that fuse and (unfortunately) it looks good. Doesn't the 5amp fuse for the "fan relay" mean that there's a separate relay unit somewhere else that may be failing? As I read more about this error code, the fan relay is coming up as another potential cause. Some DIY diagnosis sources also mention other sensors like exhaust temp and O2 as items to consider. What if a bad O2 sensor is throwing off the cooling system's readings and the cooling system is struggling to make it right?
2014 BMW i3 REX
tangocash
Posts: 24
Joined: Sat Aug 25, 2018 11:51 am
Location: Los Angeles CA.

Re: Replacing REX fuel temp/pressure sensor

tangocash wrote: Tue Sep 20, 2022 10:33 am
gta3005 wrote: Tue Sep 20, 2022 5:22 am Interesting PDF, thanks for adding that.

It did not get rid of the P14FA code. I've had that code for a long time and it tends to be intermittent so I haven't been focusing on it. I need to fic the P0480 before the end of month for inspection, so we're gonna find a solution to this!!

I have been meaning to check F72 – 5A – radiator fan relay (https://fuseandrelay.com/bmw/i3.html). I figure if the motor was shot (which it didn't seem to be in horrible condition, just minor resistance compared to the new one) then it could have fried the fuse as the vehicle was trying to run it.

I took a lot of pictures of the fan swap with the intention of creating a DIY. It's not a horrible job, took me probably 6 hours. But, if I had known exactly what I was doing from the beginning, probably would have only taken 2 or 3 hours.
I too have had the P14FA code come and go for years and, I think you're right, it tends not to trip the engine light. However, the replacement sensor that could potentially clear it is about $40 on eBay so that's an option.

Thanks for the diagram on fuses! I just checked that fuse and (unfortunately) it looks good. Doesn't the 5amp fuse for the "fan relay" mean that there's a separate relay unit somewhere else that may be failing? As I read more about this error code, the fan relay is coming up as another potential cause. Some DIY diagnosis sources also mention other sensors like exhaust temp and O2 as items to consider. What if a bad O2 sensor is throwing off the cooling system's readings and the cooling system is struggling to make it right?
Something like this?
Image
https://partsouq.com/en/catalog/genuine ... 2273826&q=
2014 BMW i3 REX
gta3005
Posts: 4
Joined: Thu Feb 07, 2019 5:23 am

Re: Replacing REX fuel temp/pressure sensor

This is promising. You're correct in that the fuse I mentioned is for a relay, so maybe this relay is bad? Do you know if its a relay that can be purchased at an Auto Zone or if its BMW specialty.

Also, regarding P14FA, where did you find the OBD2 description for this code? I haven't been able to find anything on it. And it confuses me a bit why it would be for exhaust gas temp sensor, as these are typically only for diesel engines. Also can't find anything on the i3 having an exhaust gas temp sensor and an O2 sensor is not the same as EGT sensor.
tangocash
Posts: 24
Joined: Sat Aug 25, 2018 11:51 am
Location: Los Angeles CA.

Re: Replacing REX fuel temp/pressure sensor

gta3005 wrote: Wed Sep 21, 2022 7:48 am Also, regarding P14FA, where did you find the OBD2 description for this code? I haven't been able to find anything on it. And it confuses me a bit why it would be for exhaust gas temp sensor, as these are typically only for diesel engines. Also can't find anything on the i3 having an exhaust gas temp sensor and an O2 sensor is not the same as EGT sensor.
Wow, you're right, it's hard to find details about the P14FA code and I don't understand why it's such a "secret". It's been a while since I researched it and it now took me several different Google searches to finally find something useful. I believe this is where I saw it previously, but it's the only mention I could find so I think I just ran with it as the explanation out of lack of options: https://www.engine-codes.com/p14a4_bmw.html

Could there be a glitch where a bad O2 sensor accidentally trips this misleading P14FA "exhaust" code that would normally apply to other BMW models using the same ECU software? Seems odd that you're really the only other i3 owner I've found on the forums talking about this code. Ghost in the machine?
2014 BMW i3 REX
gta3005
Posts: 4
Joined: Thu Feb 07, 2019 5:23 am

Re: Replacing REX fuel temp/pressure sensor

Damn and that's for P14A4 not even P14FA. Worth noting is I'm using Torque also to diagnose, so maybe this is a code that Torque is interpreting and not actually correct?

I'm having a friend with a bit better diagnostic tools take a look at it tomorrow so hopefully he will have a better answer. If he doesn't have a good answer I'm going to be forced to take it to BMW to diagnose. I kind of bugged out on them yesterday trying to get them to just decipher the code. Literally had the vehicle at BMW a couple weeks ago and they mentioned it had the P0480 code, but nothing about the P14FA code. So I'm trying to get them to read the code for free haha.

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