I played around with placement of the probe quite a bit, to reduce soak back when stopped (never had soak back when moving). The best location seems to be right behind the grille. While you would think that the radiator soak back would affect the readings, the forced air flow from the fan apparently offsets that.

Every other location I tried, including behind the truck and at the air intake, had more soak back.

I only saw soak back when stopped, it was never an issue while moving. I suppose you would see soak back while moving if you have the probe mounted in an area that sees almost no airflow.

Ambient temp on my drive to work was 80 degrees this morning. Intake temps fluctuated between 5-15 degrees above that once the engine reached operating temperature. My commute is 7.5 miles and takes about 15 minutes with half of the miles at 65 mph.

I've had this on for 5 months now (feels like ages ago) and a few updates.

Everything works perfectly, but after keeping the location of the probe at the side air vent, I do NOT recommend it. It can affect the reading by as much as 10 degrees C, and no matter the conditions the engine raises the temperature. It will only give an accurate reading a when you start the car.

I plan to move it when I replace my stripped power antenna motor late this year early next year. I'm thinking behind the side marker light because it's fairly sheltered and should get a good flow of fresh air. I'll update this thread when I do so.

For those of you in the North concerned about the thermometer I used only going down to -10 C (14 F), I've found that it can actually read at least down to -15 C (5 F), and I bet it can go lower. I'm not sure why the seller said it's limited to -10 C.

Bonus photo of some snow trekking

TL;DR: Put the thermometer probe in front of the engine. The cable is rather small so armor it and keep it sheltered as much as possible (unless its the sensor itself).

This is a continuation of what is already on this thread. If you want to understand why and how I got here read my earlier posts.

Over the holidays I moved the thermometer sensor from the rear of the vehicle to the very front. This task was not helped by the fact that the previous owner had sealed the grommet on the driver side fire wall. But I was also replacing my power antenna motor, so I used that grommet. If your doing this use the grommet on the drivers side.

Of course I had the essential items before I began:


The power antenna grommet is in the passenger foot well and it exits to inside the fender where the antenna resides (photo 1 & 2). From there I routed the cable through another hole used by the rear window fluid hose to get into the engine bay. From there it was simple to route it to the front of the vehicle.

1
2(the thinner cable belongs to the thermometer)

It's important to make sure the cable is protected, especially where it's exposed. My preferred style of cable protection is to use tubing with a slice running down the length of it so I can press the cable in. You can use whatever you want. I used a variety of tubing types to armor the cable.

Even with my extremely indirect cable path, I still had extra cable at the end. Because I used larger diameter hose outside I was able to double up the cable through a section of hose before taping the hose shut. If you use the drivers side grommet (which you should), you wont need as much cable as I originally suggested in my first post.

Mounting the sensor was tricky. It requires a balance of making sure the sensor is sheltered away from harsh elements while maintaining fresh air flow. It's worth noting that I submerged the sensor in flood water without issue, but protecting it is still a good idea. I mounted it behind the front grill on a cross member (3).

3 (the thermometer cable is in the clear hose, the sensor is the silver cylinder)

I took extra care to protect the wire leading into the sensor. I added heat shrink around the lower half of the probe to act as strain relief and prevent degradation from the harsh environment (4). Don't get carried away, you don't want to add so much protection that you insulate the sensor.

4 (the sensor is the silver cylinder)

Finally like all mods that add additional wires, I added a few labels (5).
5

I've driven my vehicle a lot since I did this and it's working how I hoped it would. The thermometer itself is accurate, and it no longer gets affected by engine heat despite being closer to it. Unless something breaks, this will be the last time I mess with this.

Link to the photo album updated