Nobody likes hearing that their truck has a problem during testing. But in most cases it's useful information: something in the engine or emissions system isn't working the way it should, and now you know about it.
Here's what typically happens next, and how to get from a test result to a truck that's back in compliance and back to work.
What a problem during testing usually means
For newer trucks tested through the on-board diagnostics system, problems usually show up as active or stored fault codes, or as monitors that report an emissions-related issue. For other test methods, the result may point to visible smoke or a failed component check.
Either way, the test tells you there is a problem — it doesn't always tell you exactly which part caused it. That's what diagnosis is for.
Step-by-step: what to do next
- Get a clear explanation of the result. Ask what was found and which system it relates to.
- Have the truck diagnosed. A fault code narrows things down, but a technician needs to test the system to find the actual cause.
- Review the repair estimate before any work begins.
- Complete the repair.
- Retest the truck, following CARB's requirements for your vehicle.
Why diagnosis matters before repair
Emissions-related faults can have several possible causes — sensors, wiring, leaks, a component that's failing, or a problem somewhere upstream. Replacing the most obvious part without testing can mean paying for parts that don't fix anything.
A proper truck diagnostic finds the root cause first, so the repair solves the problem the first time.
The advantage of a tester who can also fix it
When your Clean Truck Check is done by a mechanic who also does diagnostics and repair, you don't have to take the truck somewhere else, explain the problem again and wait for another appointment. As a mobile service, we test, diagnose and often repair right where your truck is parked.
After the repair, it's a good moment to think about preventive maintenance so the same kind of problem is less likely to come back.
Keep an eye on your deadline
If your truck has a testing deadline coming up, don't wait until the last week. Leave time for diagnosis, parts and a retest. For official rules about deadlines and what happens if a vehicle is out of compliance, check CARB's vehicle owner information.
Frequently asked questions
Can you fix my truck if it has a problem during testing?
In many cases, yes. We'll diagnose the cause, give you an estimate, and perform the repair once you approve it.
Will you repair anything without asking me?
No. We explain what we found and give you an estimate first. Work begins only after you approve it.