Guide · MaxxECU

EGT on MaxxECU

Any MaxxECU can read an external exhaust gas temperature amplifier on a 0–5 V analog input, set up as one of its EGT sensor functions. This guide covers the inputs, the wiring, the MTune setup and calibration, and warnings.

Checked against the MaxxECU online documentation for MTune 1.161, September 2026. Labels can differ slightly between MTune versions.

00What you need

• A MaxxECU with a free 0–5 V analog input, and MTune connected to it: 1.123 or later on GEN1, 1.158 or later on a GEN2 RACE, or 1.161 or later on a GEN2 TRACK.
• An EGX5 for the ECU's 5 V sensor supply, or an EGX12 for switched 12 V. Either one needs an ungrounded Type K probe; the kits include one.
• A multimeter.

01Pick an input

Use one of the 0–5 V analog inputs (AIN). How many you have depends on the model.

• MINI, STREET and the discontinued V1: AIN 3–4. SPORT and RACE: AIN 3–8 (on a RACE, 5–8 are on connector 2). PRO: AIN 3–18. GEN2 TRACK: AIN 1–16. GEN2 RACE: AIN 1–24.
• No pull-up. On a GEN2 input, set Pullup resistor to No pullup resistor. On GEN1, use an ANALOG INPUT (0-5V), not a TEMPERATURE input, which has a fixed 2.5 kΩ pull-up.
• GEN1 plug-in ECU: use a spare 0–5 V input on its extra connector. Many have a 3-pin Analog input 4 (0-5v) connector for this; the adapter's wiring page shows which.
• RACE, PRO, GEN2 RACE and V1 also have onboard EGT inputs for bare thermocouples. This guide is about the 0–5 V inputs.

02Wire it

• SENSOR GND must not go to engine or chassis ground. MaxxECU's wiring docs say so.
• The 5 V supply is shared, with a 150 mA limit on GEN1. An overload sets error code 17. The EGX5 draws under 2 mA.
• EGX12: power it from a fused switched 12 V feed.
• Use the sensor ground, not chassis. Every 4–5 mV of ground offset reads as about 1 °C.
• An EGX5 goes on a 5 V sensor supply only, never 12 V. It has no reverse-polarity protection either, so check red and black before you power up.
• Both outputs stay near 5 V, even in a fault. The EGX5 can't rise above its own 5 V supply, and the EGX12 is capped at about 5.3 V.

Probe side

• Kit: the probe plugs into the mini-K socket.
• Module only: yellow to the probe's +, red to −, spliced right at the module.
• Need more reach? Extend from the probe end with Type K extension wire, never copper.
• Ungrounded probes only. An ohmmeter from either lead to the sheath should read open.
• Mount the module somewhere cool, on the cabin side of the firewall or an inner fender: under 50 °C for an EGX5, under 100 °C for an EGX12.

03Set it up in MTune

1. In MTune, open Inputs → Analog Inputs and pick the AIN you wired.
2. Set Use as to Analog input and Function to EGT sensor 1. There are eight, up to EGT sensor 8. EGT sensors must be calibrated in °C.
3. Set Sensor to User defined sensor. MTune copies the previous calibration into the table, so overwrite it in the next step.
4. Click linear sensor and enter the points from the table below: 0 at 0.000 V, and 960 at 4.800 V for an EGX5 or 1250 at 5.000 V for an EGX12. Check the table it fills in.
5. Set resolution to 0.1. At 0.01 the value caps at 327.67, and exhaust temperature goes well past that.
6. Leave error detection off, which is the default. An open probe already reads hot, and a voltage limit can't tell it apart from a real overheat: in a fail-safe mode, MTune would swap either one for the Fail-safe value.
7. Connected, changes apply straight away. If you edited offline, write the tune to the ECU.

MTune's Displayed units setting changes what you see. The calibration itself stays in °C.

A dash means past that model's range.

04See it and log it

• The RealTime Data tab shows the EGT; its search box finds it.
• The Live-logger records every channel. To log on the ECU, open ECU Logging settings, turn on Enable logging and use Select channels to log.
• The default MaxxECU CAN stream carries EGT 1 to EGT 8, EGT Highest and EGT Difference.

05Optional: a warning or an engine cut

MaxxECU's EGT power cut only works with its onboard thermocouple amplifiers. For an external amplifier, MaxxECU's documentation points to Advanced warning outputs instead.

1. Turn on Enable warning system and set Used channels to at least 1.
2. Set Value to your EGT sensor and warning if to a too-high option.
3. Enter your warning level 1 and warning level 2 temperatures.
4. For a light, set a spare output's function to Warning system light level.
5. For an engine cut above level 2, turn on cut above level 2 and Enable engine cut. An open probe reads hot, so it can trigger the cut too.

06If something's wrong

MTune shows “AIN class used on 2 inputs”

Two inputs have the same function. Give each EGT its own EGT sensor number.

MTune shows “Analog / digital input conflict”

Use as was changed before the function was turned off. Turn the function off first, then change Use as.

Error code 17

The 5 V sensor supply is shorted or overloaded. 5V VRef voltage in RealTime Data should read about 5.00 V.

It reads near full scale on a cold engine

The probe is unplugged or open. Both modules drive their output high when the probe circuit is open, so an open probe reads hot, not cold.

The reading jumps with revs, fans or the alternator

You have a grounded probe, or the black wire is on chassis ground. Fit an ungrounded probe and use the sensor ground.

It reads high once the engine bay heats up

The module is mounted somewhere too hot, or there's copper wire between the probe and the module.