Guide · HP Tuners

EGT on HP Tuners

HP Tuners logs an exhaust gas temperature amplifier through the two 0–5 V analog inputs on its Pro Link or Pro Link+ cable. This guide covers what you need, the wiring, and the transform in VCM Scanner that turns volts into temperature.

Checked against HP Tuners' VCM Scanner documentation, the MPVI3 user guide and HP Tuners support articles, September 2026.

00What you need

• An MPVI3 or MPVI4 with the Pro Link+ cable, which is sold separately. Or an MPVI2 or MPVI2+ with the Pro Feature Set, which comes with the matching cable: Pro Link for an MPVI2, Pro Link+ for an MPVI2+. Without the Pro Feature Set the analog inputs don't work.
• VCM Suite with VCM Scanner: 5.0 or later for an MPVI3, 5.2 or later for an MPVI4.
• An EGX12. The Pro Link cable has no 5 V supply, so the EGX12, which runs on switched 12 V, is the straightforward choice. An EGX5 would need its own 5 V supply.
• An ungrounded Type K probe (the kits include one) and a multimeter.

01Pick an input

The Pro Link and Pro Link+ harness has two analog inputs, each 0–5 V sampled at 100 Hz.

• Red: Analog 1. Blue: Analog 2. Black: ground.
• Orange and yellow are CAN high and low. Leave them alone for this.
• On an MPVI3, the Pro Link+ cable screws onto the M8 connector.

02Wire it

• Supply: take switched 12 V from a fused circuit that's live with the key on.
• Ground to the Pro Link black wire. HP Tuners says to connect the analog device's ground there. 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 VCM Scanner

Add the analog input as a channel, then transform it from volts into temperature.

1. Right-click the channel list and choose Add Channel.
2. In Channel Selector, open External Inputs, then the MPVI folder, then Pro Link, Pro Link+. Double-click MPVI2 PL A/D Input 1 (Red) or MPVI2 PL A/D Input 2 (Blue), whichever you wired.
3. Right-click the new channel and choose Transform. In Transform Selector, pick a similar sensor from Temperature Sensors and click fx to make an editable copy.
4. Click Parameter, double-click the parameter to show the result as, and choose its units.
5. The transform reads Function: ( Input / A ) + B = Output, where A is volts per degree:
   EGX12: A = 0.004 and B = 0 for °C, or A = 0.0022222 and B = 32 for °F.
   EGX5: A = 0.005 and B = 0 for °C, or A = 0.0027778 and B = 32 for °F.
6. Add a Description and click OK. The transform saves with the channel configuration.

Box A takes volts per degree, 0.004 for an EGX12 in °C, not degrees per volt.

A dash means past that model's range.

04See it and log it

• In layouts, pick the parameter you chose in the transform.
• Gauge: right-click the gauge panel and choose its layout option, then set Parameter, Unit and Limits. Chart: do the same on the chart panel, with Limits that cover your whole EGT range.
• Use Start Scan, Stop Scan and Save. Only channels in the channel list are logged, so add and transform the channel before you start scanning.

05Optional: a visual warning

A gauge range gives you a visual warning.

1. In the gauge's Ranges, add a range from your limit to the top of the gauge and set it to show as a warning.
2. On a chart, a Reference Line at your limit makes it easy to spot in a log.

06If something's wrong

It reads about 340 °C (an EGX12) with nothing connected

An unconnected Pro Link input sits at about 1.34–1.37 V, not 0 V. Check the signal wire, and that the channel is the input you wired. HP Tuners' own test is a fresh AA battery on the input, which should read about 1.5–1.6 V in the Value column.

Every reading is off by the same amount

A ground offset between the harness and the amplifier. On an EGX12, 0.1 V of offset is 25 °C. Fix the ground first; B in the transform can trim what's left.

The analog channels don't work on an MPVI2 or MPVI2+

That interface doesn't have the Pro Feature Set. It's standard on an MPVI3 or MPVI4 but sold separately for an MPVI2 or MPVI2+.

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 run the black wire to the Pro Link black wire.

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.