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Part# 08-07462
MFR Model# AT5K


High internal resistance in spark plugs is rapidly becoming a concern that many IA/AP's are beginning to recognize as the source of rough running engines and chronic magneto related problems. Since a growing number of maintenance facilities are incorporating a resistance check of all spark plugs, Tempest felt it would be beneficial to make it as easy and efficient as possible to conduct such a test.

AT5K Resistance Tester
Tempest has developed an easy-to-use tester that makes it very efficient for IA/AP's to test the resistance in all aviation spark plugs.

The IA/AP simply places the spark plug, barrel side down over the contact post and touches the other lead end to the firing end of the center electrode. If the light is green, the spark plug resistance is below 4kŮ (thousand ohms). If both the green and red lights are on, then the plug is between 4 - 5kŮ. This is acceptable for serviceable plugs. If the red light is on alone, this indicates a resistance value in excess of 5kŮ and the plug must be discarded and replaced.



Would prefer a built in OHM gauge on the unit, but the unit is well made and should provide years of good service. It is easy to use

Paul T
October 5, 2019

Works great, simple and quick. No reason not to check plugs when they are out when you have this great little unit. You can accomplish the same thing with an ammeter but not as quick and easy. Im happy with it, highly recommend.

October 13, 2017

Both O-rings pulled off on the first plug. Other than that it works great. I found the faulty plug that had been bothering me right away. What a time saver.

Tom F
July 29, 2019

Seems to work well, very easy to use.

Glen B
December 10, 2018


Q: Does this Tempest AT5K resistance tester work on Champion plugs as well as Tempest?

Yes, both plugs types will work fine with this tester.

Q: Will this Tempest AT5K Resistance Tester work with both massive and fine wire plugs?

Per the supplier: Yes, it will work with both types of plugs.

Q: How is the Tempest AT5K resistance tester powered?

This is powered with a 9V battery.

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