How to check spark plugs with a multimeter and what is important to know when replacing them

Homemade cars / Useful and interesting 105 825 5

Hi all! Today I will show and tell you how to check a car’s spark plugs with a regular multimeter. Let's imagine a situation where you drove 30-40 thousand kilometers on spark plugs alone and decided to check them. But how to do that?
Also at the end you will find very useful information on what you need to pay attention to when replacing spark plugs with new ones.

Checking spark plugs with a multimeter

So, let's take multimeter and set it to measure resistance up to 20 kOhm. Then we take the spark plugs one by one and check their resistance between the central electrode and the contact nut.

If the spark plug is working properly, then multimeter should show a value in the range of 2.5-8 kOhm. If it is different, then it is better to replace the spark plug with a new one.

Using this method, we check the internal resistance of the spark plug's built-in resistor.

Useful advice for those who change spark plugs to new ones

If you decide to replace the spark plugs with new ones and bought an unfamiliar manufacturer, then be sure to check the resistance of the spark plugs using the example above.
The fact is that there are special spark plugs with zero internal resistance, made for a specific type of engine.

And if you accidentally put such spark plugs in your engine, then there is a very high probability that the central control controller will burn out. This is exactly what happened in my case.

Result:

Here I checked 5 of the candles found. 2 pieces were with zero resistance. Of course they work, but they don't fit my car.

Watch the video

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come back

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Comments (5)

#1 Vladimir Guests October 26, 2019 10:07
15

It’s true that the spark plugs may not fit. In order to check the spark plug, you need a special stand that measures the pressure in the combustion chamber.
- Answer
#2 Yura Razborkin Guests 29 December 2020 17:59
12

Particularly damning in its nonsense is the statement that if you install spark plugs without an internal resistor, then some kind of control controller will burn out)))) I, as an electronics engineer and professional diagnostician-repairman, propose to delete this article so as not to produce stupid collective farm tales among ordinary motorists.
And now, author, read carefully - I will reveal to you more than one “America”)))
1. A resistor is installed in a spark plug for one purpose only - noise suppression from a spark discharge. And even if you don’t take into account that the central core of the explosive wire also has a resistance of 2-6 kOhm (for the same purpose - noise reduction), then this is not for the health of the internal combustion engine control controller (by the way, you would have decided - a switch or an internal combustion engine control controller))) it will simply have no effect (although it may well turn out that someone tricked you into replacing him with such a stupid justification)
2. Such a miracle test of the spark plug is absolutely pointless, because you are simply checking the wrong thing - you don’t need to call the central electrode, but take a megger (megger) and measure the resistance of the spark plug insulator.
3. In general, the best way to check a spark plug is to test it on a bench UNDER PRESSURE.
- Answer
1. #3 Valery Guests March 22, 2021 10:11
  1
  
  You are right Yuri, measure as it is written here.
  
  Answer
#4 Guest Sergey Guests May 28, 2021 00:57
0

Do you discard the temperature regime? - the stand will not help in this case.
- Answer
#5 Guest Andrey Guests 13 July 2021 10:14
0

Thank you!!!
- Answer