OBD2 code readers
Prices and specs checked October 27, 2026
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Concern
The check engine light comes on, and you don't know if it's a loose gas cap or something that needs a shop today.
Cause
Cars and light trucks from 1996 on have an on-board diagnostic system, called OBD2, that watches the engine and emissions parts. When it sees a fault, it turns on the light and stores a trouble code. A steady light means it found a problem worth fixing soon. A flashing light usually means a misfire that can damage other parts, such as the catalytic converter.
Correction
A code reader plugs into the OBD2 port under the driver's side of the dash and tells you which code is stored. That tells you where the problem is and how urgent it is before you call a shop. If the light is flashing, or the car shakes or loses power, pull over safely and shut it off instead.
Your pick
For most drivers
Innova 5210
$89.99 at Walmart, sold by Innova; $99.99 on sale at Innova (regularly $119.99)
- Type
- Handheld with its own screen. Works without a phone.
- Reads
- Check engine and ABS brake codes, with code severity
- Emissions
- Smog readiness check and drive cycle procedures
- Extras
- Battery and charging system test, oil light reset, live data
- App
- Optional free RepairSolutions2 app over Bluetooth
- Warranty
- 1 year
Pick it if
You want a tool that lives in the glovebox and tells you what the check engine or ABS light means, without pairing a phone.
Skip it if
You also want airbag codes or tire pressure readings. Innova's 1000 adds those at the same price, but it needs a phone.
Innova 5210 on Innova's site
Your pick
For phone users who want more warning lights covered
Innova 1000 (CarScan Mobile)
$99.99 on sale at Innova (regularly $119.99)
- Type
- Plug-in Bluetooth reader that uses an iPhone or Android app
- Reads
- Check engine, ABS and airbag (SRS) codes, with an all-system scan
- Also reads
- Tire pressure sensors, transmission temperature, brake pad life
- Extras
- Battery and charging test, battery reset after replacement, oil light reset, live data graphs
- Subscription
- None. Updates are free.
- Warranty
- 1 year
Pick it if
You're comfortable using your phone and want one tool for the check engine, ABS and airbag lights, plus a battery reset when you replace the battery.
Skip it if
You'd rather not depend on a phone and an app, or you share the car with someone who won't use one. Get the 5210 instead.
Innova 1000 on Innova's site
Your pick
For the check engine light only, on a budget
TOPDON ArtiLink300
$34.00 at TOPDON, sold out there when we checked; $31.86 at Walmart from a marketplace seller
- Type
- Handheld with a 1.77-inch color screen
- Reads
- Reads and clears engine codes, freeze frame data
- Emissions
- I/M readiness status
- Extras
- O2 sensor test, live data with graphs, 12-volt battery test
- Updates
- Free for life
- Warranty
- 1 year
Pick it if
You mainly want to know why the check engine light is on, or whether the car is ready for an emissions test, and you want to spend as little as possible.
Skip it if
An ABS or airbag light is on. TOPDON doesn't list ABS or airbag codes for this model, so it can't tell you what those lights mean.
ArtiLink300 on TOPDON's site
Before you buy
Every OBD2 reader can read check engine codes on a 1996 or newer car, because that part is standard. ABS, airbag and tire pressure systems are not standard, so coverage for those depends on the make, model and year. Both makers say features vary by vehicle and offer coverage checkers on their sites. Check your car before you pay for features it may not support.
A code tells you which system flagged a problem, not which part to buy. The same code can come from a bad sensor, a wiring problem or something upstream of both. Treat the code as the starting point for a diagnosis.