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Discussion Starter #1
Hello everyone, and thank you for any help.


I am driving myself crazy trying to find the location of the Coolant Temp sensor on my 17 Focus RS. My stock one is fried and showing the temp as pegged hot, but the car is running fine/no issues. It fried when there was low coolant in the system. I got a new sensor but I cannot find ANYWHERE just something pointing out where this thing is!!


- TXRFAST
 

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Hello everyone, and thank you for any help.


I am driving myself crazy trying to find the location of the Coolant Temp sensor on my 17 Focus RS. My stock one is fried and showing the temp as pegged hot, but the car is running fine/no issues. It fried when there was low coolant in the system. I got a new sensor but I cannot find ANYWHERE just something pointing out where this thing is!!


- TXRFAST
On the drivers side end of the head you will see a rectangular black plastic adaptor with hoses going into and out of bolted to the head. The coolant temp sensor is on this fitting. There is also a CHT (cylinder head temp) sensor mounted on the back of the head near the turbo coupling to the head.
Manual ref 303-14D

Ciao
 

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Discussion Starter #6
I am currently fixing the car. The sensor was easy enough to replace, although the angles are a bit strange @ times. Turning it back on I notice the guage s still pegged hot. However, I unplugged the battery and will reconnect in a few hours to check if its reading normal.

I do hope this fixes is or I just wasted $120 on stuff and will be back to square 1.

Car runs fine but this is quite annoying.
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I am currently fixing the car. The sensor was easy enough to replace, although the angles are a bit strange @ times. Turning it back on I notice the guage s still pegged hot. However, I unplugged the battery and will reconnect in a few hours to check if its reading normal.

I do hope this fixes is or I just wasted $120 on stuff and will be back to square 1.

Car runs fine but this is quite annoying.
View attachment 339033
The reason I asked for an update after the replacement was I had doubts the sensor would fix the issue but wasn't 100% and didn't want to rain on your parade. The gauge temp is inferred from the engine ecu not a direct reading from the engine sensor. It may well be the gauge itself or a signal issue from the ecu.

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I am currently fixing the car. The sensor was easy enough to replace, although the angles are a bit strange @ times. Turning it back on I notice the guage s still pegged hot. However, I unplugged the battery and will reconnect in a few hours to check if its reading normal.

I do hope this fixes is or I just wasted $120 on stuff and will be back to square 1.

Car runs fine but this is quite annoying.
View attachment 339033
I had my doubts it would but didnt like to say considering you already bought the sensor. The manual says if the gauge doesnt work or reads wrong go into dealer mode and do a gauge sweep test and if it fails replace the IPC instrument panel cluster.
If it loses a signal from the BCM for more than 5 seconds it defaults to cold and sets a fault code less than 5 seconds or invalid it defaults to the last known good temp indication

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Discussion Starter #9
So after 2 hours of the ground terminal and positive being disconnected it's still doing the same thing.

I'm really not sure what @ this point is causing the dash to read it's running hot. It makes no sense.

Seems as though the information is not automatically fed from the sensor, but the ecu. Otherwise the resistance decreases over time as temp increases on the engine making the needle go higher. It literally pegs hot before you even start warning of high temp.

Something is a miss :sneaky::unsure:
 

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Discussion Starter #10 (Edited)
I had my doubts it would but didnt like to say considering you already bought the sensor. The manual says if the gauge doesnt work or reads wrong go into dealer mode and do a gauge sweep test and if it fails replace the IPC instrument panel cluster.
If it loses a signal from the BCM for more than 5 seconds it defaults to cold and sets a fault code less than 5 seconds or invalid it defaults to the last known good temp indication

Ciao
You are definitely an angel in human form. I cannot thank you enough for the input. It seems the gauge sweep shows the needle works, but it goes back to pegged hot after the sweep test.

Given that she is otherwise fine, I'm going to try a few other things with an access port to see if this can be fixed. It does seem to be an ecu issue. Never gonna give up on my girl. 🥰

Thank you.
 
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