Check engine light on? You won't pass emissions.
In Tucson, a vehicle can't pass its emissions test with the light on — and you can't renew your registration until it passes. We'll find out why it's on and tell you exactly what it will take to fix.
About an hour. You don't have to have bought your car from us.
A code is not a diagnosis
The free scan at the parts store reads a code and points at a part. That's a starting point, not an answer — the same code can come from a failed sensor, a vacuum leak, bad wiring, or a problem somewhere else entirely that only looks like a sensor fault.
Plenty of people buy the part the code named, install it, and the light comes back on. Then they've spent the money and still can't register the car.
We test, not guess
Live data, circuit testing and manufacturer diagnostic procedures on the actual system, until we know what's failing and why.
You get it in writing
What's wrong, what it costs to repair, and whether it's what's blocking your emissions test. In plain language, with photos.
Your $89 comes back
Have us do the repair and we credit the full $89 toward the work. If you'd rather take the report elsewhere, it's yours.
Two things worth knowing before your test
- Clearing the code does not fix it. Disconnecting the battery turns the light off, but it also erases the readiness monitors — and a vehicle that isn't ready gets rejected at the station too.
- You can test up to 90 days before your registration expires, so there's time to fix the problem properly if you start now.
Bring your renewal notice if you have it. It tells us whether a test is actually due on your vehicle this year, which sometimes saves you the trip entirely.
If the repair is more than you planned on
0% for 90 days on repairs over $350
We finance service work through DigniFi. Applying takes a couple of minutes at the counter. Ask your advisor when we go over the diagnosis.
Book your diagnostic
Fill this out and we'll call you to confirm a time. Prefer to skip the form? Call or text 520-888-0910.
We'll only use your information to schedule this appointment.
Where we are
1602 W Prince Rd, Tucson, AZ 85705
Service hours
Monday through Friday, 8:00 to 5:00. Closed weekends.
How long it takes
About an hour, and we'll walk you through the diagnosis before you leave.
Anyone is welcome
You do not need to have bought your vehicle from us. We service all makes.
Check engine light diagnostic is $89 plus tax and applies to gas vehicles only; diesel quoted separately. The $89 is credited toward the cost of repairs performed at Cactus Auto Company. Some concerns require additional diagnostic time, which we will quote before proceeding. Cactus Auto Company is not an emissions testing station and does not perform state emissions tests. Financing through DigniFi is subject to approval; 0% for 90 days applies to qualifying repairs over $350. Offer expires October 31, 2026.