Interactive demo
Look up a check engine code
Type a code and see what it means, whether you can keep driving, what usually causes it and what the repairs cost.
Pick a scenario
Free, no account needed.
A scripted demo with example data. In the app, answers and results are made for your own car and situation.
OBD-II Trouble Codes Explained
An OBD-II code is the standardised label your car's computer stores when it detects a fault. The code names the symptom the computer saw, not the part that needs replacing.
How to read a code
Every code starts with a letter identifying the system: P for powertrain, B for body, C for chassis and U for network.
Emissions
Catalyst System Efficiency Below Threshold (Bank 1)
Yes, in most cases
Catalyst System Efficiency Below Threshold (Bank 2)
Yes, in most cases
Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
Yes
How it works
- 01
Enter the code
From your scanner or a free reading at a parts store.
- 02
Know if you can drive
A clear verdict first, with the warning signs to watch for.
- 03
Fix the right thing
Causes ranked by how common they are, and the cheapest checks first.