EGT #1, shows -99 deg.

[carl_nank]

EGT #1, shows -99 deg. with the engine off (reading ambient air temperature). The rest of them read the ambient temperature correctly at 56 degrees, after second engine start & taxi run. It worked OK before, during and after the first engine start. I switched #1 probe wires to #3 at the harness connection in the engine compartment. The problem moved to number 3, so it appears the probe is bad. I removed the probe and cleaned it up but, no joy.

Do I need a new probe?

Carl Nank

 

[PhantomPholly]

It is usually a connection problem, but you can test this by switching the connections between two probes. If the problem follows the probe, it may be a bad probe.

Also, search the forum on the words "burned" and "EGT"

 

[carl_nank]

I did switch connections between probes as stated above. I left the problem probe in the #1 exhaust and switched the connections so the # 1 probe would be on the #3 circuit. The problem moved to the #3 circuit so, the #1 probe has been isolatred as the problem.

Should the probe be replaced or can it be fixed?

Carl

 

[dynonsupport]

The probes generally aren't repairable, and they're not expensive, so you should probably just replace it.

One simple test you can do in your case is continuity- -99 almost always means an open probe, so you can just use an ohmmeter to read the thermocouple. It should be 0 ohms, but I bet yours is open.

 

[DBRV10]

make sure the pin in the CHT/EGT harness connector is not being pulled back out of the connector body.

We have discussed this elsewhere, and is a problem with a large bunch of thermocouple cable in the back of a connector.

DB

 

[carl_nank]

One simple test you can do in your case is continuity- -99 almost always means an open probe, so you can just use an ohmmeter to read the thermocouple. It should be 0 ohms, but I bet yours is open.

I did use the OHM meter to measure continuity between the red and yellow wires on the probe and found the circuit open. I was not sure what I was supposed to find, so I thank you for your explanation. I did also measure the good probe I measured continuity. So Thank you for confirming. I will order a new probe.

Does this happen often for a open to occur on new installations? I was wondering if I had some kind of engine problem that caused this on second engine start?

Thanks for your help,

Carl

 

[jakej]

Does this happen often for a open to occur on new installations? I was wondering if I had some kind of engine problem that caused this on second engine start?

In a word, no I've done many installations and found only 1 sensor DOA.

Jake J

 

[carl_nank]

Actually, it was not DOA. It worked fine for 1st and 2nd engine start. It went bonkers on taxi test.
Carl