EGT Probe

TRE Exhaust Gas Temperature (EGT)

Thermocouple Installation Instructions for the TRE EGT probe

NOTE: Thermocouple wire codes:



Don’t ask me why, but this is the industry standard.  Your wiring colors may vary and may require these wires be reversed.

Thermocouple installation tools needed and found at the local hardware store if you don’t have them already.

Use 11/32″ H.S.S. Drill Bit
Use 1/8″-27 National Pipe Thread Tap


Thermocouple Compatibility:

Compatible with all 2 wire K-type gauges. (Apexxi,  Autometer, Blitz, Greddy, HKS, Ispro, Percys, VDO, Westach, etc..)

Thermocouple Accuracy: 

@ 1000* F  +/- 35 Deg F.*
@ 1600*F  +/-  25 Deg F.*

Thermocouple Temperature Rating:

Max continuous: 1700*F.
Melting point:   2150*F.


Ideal Exhaust Gas Temp:

Most engines average 1400 – 1600*F @ WOT but many things will affect exhaust gas temps such as; fuel type, compression ratio, air/fuel ratio, ignition timing, intake air temp, fuel type, etc…

Thermocouple Life Expectancy:

20,000 to 30,000 miles depending upon the application, environmental and fuel being used.  High temps will reduce the service life.

Thermocouple design:

A K-type thermocouple is made by connecting a Chromel wire and an Alumel wire in a shielded junction. If one of the two dissimilar wires is made warmer than the other, then the thermocouple will generate a small voltage signal. .  The fast response is due to their low mass and because of it they do not last long where temperatures exceed their limits.  Handle with care and do not exceed max temps.

Thermocouple location:

Location of the thermocouple should be no closer than 4 inches from the back of the valve.  The probe junction should not touch any metal (false readings). The thermocouple should be mounted in the exhaust stream before the turbo.  It will be assumed that EGT’s are to be monitored as an individual preference and TRE is not to be held responsible or liable for any damage while using these thermocouples.

Drilling & tapping:

Use plenty of oil dark thread cutting oil during the drilling and tapping operation for the best results. Because the threads are on a taper you will wan to check the fit while tapping the threads.  Stop halfway and check to make sure you don’t over cut the threads or the probe may not tighten up fully.  You will want to check how far the probe threads in and leave between 2-4 threads exposed.  Use a Nickel-base anti-seize on the threads and do not over-tighten probe.

Sending Wire Routing:

First use the proper wire.  Speaker wire will work but we recommend using the high quality EGT wire that we sell.  It’s has a nice Stainless Steel braided outer jacket which protects the wires against abrasion and looks good and the wires are Kapton insulated.

Wire is to be passed through the firewall then the connectors are to be installed. Secure the sending wire to the body every 12 inches with plastic cable ties. Ensure the sending wire is passed through the firewall with care. Proper routing is crucial to avoid system shorts.  For those who don’t know, you can wind it in a helix to suppress noise.

Installing Sending Wire Connectors:


Slide back 3/4″ (~19mm) of the stainless steel outer sheath.
Strip 1/2″ (~12mm) of brown outer insulation, to expose the red and yellow sending wires.
Strip 1/4″ (~6mm) of red, and yellow insulation, exposing the bare thermocouple wire.
Remove the cover screw, and cover on the supplied connector jack (jack to wire hold-down).
Insert the thermocouple wire simultaneously through the correct holes in the end of the jack.
Red sending wire into the hole marked Negative (-).
Yellow inserted into the hole marked Positive (+) , making sure exposed thermocouple wire is deep enough into the jack, and the wire is lined up with its contact patch inside the jack.
Replace jack cover, tighten connector screw, and insure the sending wires are secured in the jack.
Continue to follow the polarity of the jack connector, connect jacks to the thermocouple sending unit in the engine bay, then to your EGT gauge. Enjoy.