In my first and second posts, I went over the basic tools needed to get started in working on your own car. Now that you have the tools to do the work, It’s time to go over what you’ll need in order to diagnose the problem so you know where to start.

Get connected: a Bluetooth scanner
~$10-$20

If you have a car made in or after 1996, do yourself a huge favor and pick one of these things up as soon as you can. These little tool can help figure out a lot of the issues that the ECU sees during operation. You just have to pair the Bluetooth adapter to your phone, install a diagnostics app (like Torque, which is what I use) and then scan your codes. Many apps will allow you to see the current fault codes (when your check engine light is on), pending codes (stored in ECU but won’t cause harm) and read all kinds of sensor values (coolant temperature, oxygen sensor values, etc.). The pro version of Torque (~$5 to buy) also allows you to do performance tests like 0-60 times and estimate HP figures. This cheap adapter on Amazon will only cost you $13 and is rated very well.

A shocking discovery: Multimeter
~$5-$30
When electrical gremlins start attacking your car there is really only one tool to use for sniffing them out: the multimeter. These handy little tools can do a lot of different things. They can measure voltage to see if a sensor is reading properly, check resistance to find out if a plug wire is toast, and check amperage to see  if a unseen load is draining your battery, as well as many others. I use this back-lit multimeter from Harbor-Freight as it’s inexpensive and performs most of the tasks I need it to. At $6, it’s worth having a couple and if you plan your trips to HF right, you can even pick it up for $0, what a bargain!

The doctor is in: Mechanic’s stethoscope
~$5-$30
When your engine starts making strange noises and there’s no  check engine light or running data in the ECU to indicate what the problem may be, it’s time to start manually checking. This is where a mechanic’s stethoscope comes in to play. You can use the stethoscope to pin-point, or at the very least narrow down, what the problem may be. A mechanic’s stethoscope works just like a doctor’s stethoscope, amplifying the noise and sending it to the earpiece, so you only hear the noise you need to hear. To use the stethoscope, simply put the ear piece in your ears and hold the probe end on to the part you suspect is the culprit while the engine is running (good parts will make a rolling noise, bad parts will make a grinding noise). This $7 option on Amazon is rated decently and won’t break the bank. In a pinch, using a long screwdriver with the plastic end against your ear can also work (it’s an old hot rodder’s trick).

A flash of brilliance: Spark Checker
~$10
 When your car has a misfire it’s often hard to tell what’s causing it. With an in-line spark checker you can determine if it’s an electrical or mechanical issue. All you have to do is disconnect a spark plug wire from a spark plug and place the spark checker in between them. If the light on the checker glows when you crank the engine, then you’ve got spark. At $5, the model that Harbor Freight sells is a worthwhile investment for anyone whose car has spark plug wires. I’m not sure how well they work with coil-on-plug style setups as I’ve never tried them this way. An added bonus of this tool is you don’t have to risk shocking yourself trying to hold a spark plug against a ground.

That does it for this week’s installment of Toolbox Tuesday. Next week, I’ll go over tool storage and organization. I’m currently working on breaking down the cost of all the tools I’ve mentioned in the blogs into an easy to read spreadsheet on Google Drive so keep a look out for it shortly.

If you have any ideas for future topics, suggestions for tools I may have missed, or just feel like saying hello feel free to post it in the comments.

Happy wrenching!


Wilson Oberholzer is  a full time mechanical designer with a very heavy background in manufacturing and tinkering. He’s done everything from the basics like changing oil all the way up to advanced stuff like rebuilding engines and wiring in new engine management equipment.