Guides
Guides
Longer explanations of how the systems in your car report faults, and what to do about them.
Exhaust and catalyst
Emissions and evaporative
Readiness monitors, and why a car with no light still fails
An emissions test checks more than the light. What readiness monitors are, why clearing codes resets them, and how to get them to run again.
Loose gas cap, or a real evaporative leak
Three codes cover evaporative leaks and they differ only by size. How to tell a cap from a genuine fault, and why the test takes days to confirm.
General
Variable valve timing codes, and why they start with your oil
P0011 and P0016 look like expensive mechanical faults. Often they are, but oil condition sits behind a large share of them and is checked first.
What a generic OBD-II adapter can and cannot read
Generic OBD-II covers engine and emissions. What that includes, what it leaves out, and why ABS and airbag codes need different equipment.