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Having the right tools in your garage can make all the difference when it comes to diagnosing and resolving issues with your vehicle’s engine. With onboard computers and complex systems in modern cars, you need more than just a basic set of wrenches and screwdrivers. Advanced diagnostic tools help pinpoint problems quickly and accurately.

In this guide, we’ll cover the top 5 engine diagnostic tools that every DIY mechanic should have. We’ll look at what they do, examples and prices, and when each tool is most useful. We’ll also go over factors to consider when selecting diagnostic equipment. By the end of this article, you’ll have a solid understanding of must-have diagnostic tools to troubleshoot your engine and keep your vehicle running smoothly.


Having a reliable vehicle is important, but engines can be complicated. When the dreaded check engine light illuminates, it could point to dozens of different issues, ranging from minor to major. Without the proper diagnostic tools, tracking down the exact cause can be like finding a needle in a haystack.

The good news is that advancements in diagnostic technology have made engine troubleshooting much easier for the average DIY mechanic. Gone are the days when you had to guess what was wrong based on basic measurements and visual inspections. Modern scanners and testers allow you to pinpoint problems quickly and accurately.

In this guide, we’ll explore the top 5 engine diagnostic tools that every DIYer should have in their toolkit:

  1. OBD2 Scanner
  2. Digital Multimeter
  3. Compression Tester
  4. Timing Light
  5. Borescope Camera

We’ll look at the key features and benefits of each tool, examples and pricing, when to use them, and any limitations. We’ll also go over factors to consider when selecting diagnostic tools for your needs and skill level. Let’s dive in!

Top 5 Engine Diagnostic Tools

1. OBD2 Scanner

An OBD2 scanner is the most basic diagnostic tool that every mechanic should own. OBD stands for On-Board Diagnostics generation 2, which refers to the standard diagnostics system built into all vehicles manufactured since 1996.

The main purpose of an OBD2 scanner is to retrieve trouble codes from the engine control unit (ECU) when the check engine light comes on. It connects to the diagnostic port usually found under the dash. Here are the key benefits of OBD2 scanners:

OBD2 scanners vary widely in price and capabilities. Simple code readers can be had for as little as $20, while advanced professional-grade scan tools run over $1000. Some popular mid-range options are:

The limitation of basic OBD2 scanners is that they only read generic codes common to all cars. For detailed manufacturer-specific codes and data, you’ll need an enhanced scanner. However, a code reader is the essential first step in diagnosing check engine lights and is useful for do-it-yourselfers.

2. Digital Multimeter

A digital multimeter (DMM) measures electrical values like voltage, current, and resistance. Having a DMM enables you to diagnose electrical issues and check if components are getting power and working properly. Key features include:

You can get a basic digital multimeter for around $50, or pay over $100 for one with more advanced capabilities from brands like Fluke or Klein. When choosing a DMM, look for:

A digital multimeter is useful anytime you need to test an electrical circuit:

The main limitation is that a DMM only measures fixed circuits. For live data you’ll need a scope or scanner. But a DMM is cheaper and easier to use than a scope for basic tests.

3. Compression Tester

A compression tester is used to measure the compression pressure inside the cylinders. Compression issues can cause poor performance, hard starting, and misfires. Here’s how a compression tester works:

Look for a compression tester kit that includes:

Prices range from around $40 for basic testers to $200 for commercial grade kits with better gauges and accessories. Brands like OTC, INNOVA, and Craftsman make affordable testers suitable for home mechanics.

The main uses for a compression tester include:

Compression testers have some limitations:

Still, a compression tester is a vital tool for assessing the internal condition of your engine.

4. Timing Light

A timing light is used to check ignition timing by visually inspecting the timing marks on the crankshaft and camshaft pulleys. Timing refers to the precise moment when the spark plug fires relative to piston position. Here’s how a timing light works:

Basic timing lights cost around $50. Look for a light with:

Proper ignition timing is crucial for engine performance and preventing damage. Symptoms of bad timing include:

Using a timing light allows you to check for:

The main limitation of timing lights is that they only work on older distributor-based ignition systems, not modern computer-controlled engines. But they still have use for inspecting timing components.

5. Borescope Camera

A borescope is a flexible inspection camera that allows you to look inside the cylinders and down intake ports. Having a visual of the engine internals can reveal issues like:

A basic 1 meter borescope can be purchased for around $100. Look for one with:

While borescopes take practice to use properly, they are invaluable for diagnosing internal engine issues without major disassembly. Limitations include:

Even with these limits, a borescope allows you to inspect areas impossible to see otherwise. The insights it provides are well worth the cost for any serious mechanic.

How to Choose the Right Diagnostic Tools

With the top 5 engine diagnostic tools covered, how do you determine which ones to get for your needs and skill level? Here are some tips:

The right diagnostic tools save a ton of guesswork and frustration when dealing with engine issues. Invest wisely and build your capabilities over time, and you’ll have the power to accurately pinpoint problems across many systems and vehicles.

Frequently Asked Questions on Engine Diagnostic Tools

What is the check engine light and how can an OBD2 scanner help?

The check engine light (CEL) illuminates when the vehicle’s OBD system detects an issue. An OBD2 scanner lets you retrieve diagnostic trouble codes that help identify the problem. Without scanning the codes, you don’t know what’s wrong when the CEL comes on.

Should I buy an inexpensive or expensive OBD2 scanner?

It depends on your needs. A basic inexpensive code reader is fine for DIY use to read and clear generic check engine codes. For advanced diagnostics, live data, and manufacturer-specific OEM codes, an expensive professional-grade scanner would be better.

What features make a digital multimeter useful for diagnostics?

Key DMM features include voltage, current, and resistance measurements, continuity testing, diode testing, signal measurement, and accuracy. These capabilities let you check electrical circuits critical for diagnosing problems.

When would I need a compression tester?

Check compression when an engine has a misfire, lacks power, burns oil, starts hard, or has high mileage. Compression testing can detect leaks, bad rings, burnt valves, and other internal mechanical issues.

Why is a timing light important?

A timing light lets you visually inspect cam/crank timing marks while the engine is running. This is necessary to check for timing chain slack, jumped timing, and issues with variable valve timing components.

How does a borescope camera allow you to see inside the engine?

A borescope uses a thin flexible cable with a camera on the end. It can be inserted through any small opening to look inside the engine. This allows you to visually inspect cylinders, valves, pistons, and other internal components.


Diagnosing modern engine issues requires having the right tools for the job. While a basic socket set is still essential, new problems require advanced diagnostic capabilities. With the technology built into vehicles today, it’s impossible to troubleshoot effectively without scanners and testers.

We’ve covered the 5 most important engine diagnostic tools that should be in every DIYer’s toolbox. Start with essentials like an OBD2 scanner and multimeter. Then add tools like compression testers, timing lights, and borescopes as your needs and skills grow. Diagnostic equipment is an investment, but it pays for itself many times over by empowering you to keep your vehicles running right.

Remember to build up your diagnostic knowledge alongside your toolkit. Learn how to use OBD2 scanners to their full potential. Practice testing components like alternators, starters, sensors, and circuits with a multimeter. Study up on compression and timing specifications. And get the knack of maneuvering a borescope camera inside tight spaces. Developing your skills will ensure you get the most out of any tool.

With this guide, you now have an overview of the top 5 picks for engine diagnostic equipment. The right tools combined with your mechanical know-how will have you tracking down and fixing issues like a pro. Drivers no longer have to simply guess at what could be wrong with their check engine light on. Arm yourself with the power to diagnose and resolve engine problems quickly and with confidence.

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