2008 MP8 pyrometer probe?

[ChicagoJohn]

I have been to my Mack dealer 3 times trying to figure out which probe is the correct one to power the exhaust temp gauge. There's like 4 different probes on the exhaust pipe. Anyone ever change one and know which probe to change?

There's one right behind the turbo, one before the dpf canister, and another after the canister and lastly one on the pipe after the EGR cooler. I know it's not the one after the EGR cooler. I was thinking it was the one after the dpf system since the gauge showed hot during a regen.

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[Mackpro]

I was thinking its the one right as the exhaust goes into the tp  DPF assembly ( assuming its the under cab model and not the stand up DPF) . If its fauty you should get a fault code otherwise it could be the dash cluster

[ChicagoJohn]

I was thinking its the one right as the exhaust goes into the tp  DPF assembly ( assuming its the under cab model and not the stand up DPF) . If its fauty you should get a fault code otherwise it could be the dash cluster

I was thinking the same thing. At first I thought it was a computer issue because I had the dpf delete, but after digging through the computer, w found the setting and made sure it was turn on. I'm not getting any fault code, but the wire looks a little worn. I do have the stand up dpf that's under the passenger door. A shop said I should use an ohm tester and see it I get a reading. I was going to try that when I had a chance.

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[Mackpro]

Yea if you got a DPF delete software installed it might not look at that sensor and your guage wouldn't show a reading and also no fault code

[ChicagoJohn]

So I started to test the different plugs and then got side tracked yesterday. So, I thought I'd post pics off every probe I have and see if anyone knows.

This first one is coming out of the EGR cooler, so I know it's not that one.

This I believe is the 7th injector.

Here's where it gets murky. This probe is after the 7th injector, but before the dpf tower.

Here's the side of the dpf filter, which has 4 probes.

This one is immediately after the dpf filter.

And lastly this one is father back in the exhaust pipe before the Y split for the exhaust stacks.

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[ChicagoJohn]

To update, I tested an the probes with an ohm meter. I ended up changing the larger one before the dpf housing. My gauge still isn't working. So I'm wondering if either I need to replace another sensor or am I suppose to clear the codes before it'll start working. I'm showing a fault code 140 pid/sid 173- exhaust has temp

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