The second opinion that protects your wallet.
"I just got quoted $3,800." Before you sign that estimate — get a second opinion built the way a good diagnostician actually works: evidence first, verdict last, and an honest list of what your problem isn't.
No proprietary hardware, no parts commission. Plug in any $22 Bluetooth adapter, print the case file, and hand it to your mechanic — you're paying for the fix, not the guessing.
The same loop a great diagnostician runs — never guess-and-replace.
Repair paperwork, trouble codes, photos, sounds — and a live OBD scan the app directs through a cheap Bluetooth adapter. What already exists decides most cases.
Honest probabilities from your vehicle's documented failure history — not generic internet guesses.
The single cheapest question, photo, driveway test, or targeted OBD scan that separates the leading suspects.
A ranked verdict, the don't-buy list, and a case file you can print for your mechanic.
Open the Kia and work a case yourself, or replay the documented F-150 case to see how it ends.
Same case, same steps — flip to see it on either platform. iPhone now, native Android on the way.
Case history stays alive while a vehicle is active. Lapsed vehicles go read-only for 90 days with export, then are deleted.
Before anyone theorizes, RootCause collects what already exists.
RootCause never directs work on brake hydraulics, SRS/airbags, or pressurized fuel — those hand off to a shop, every time.
Plenty of apps read codes. None of them keep a case file, weigh evidence honestly, tell you what not to buy, or hand you a printout for the shop.
Every answer, photo, and test result accumulates per-vehicle. The verdict cites its evidence — and keeps getting smarter about your exact vehicle.
The most valuable sentence in a diagnosis is "it's not the head gasket." Every verdict names the expensive repairs the evidence argues against.
Walk in with the diagnostic already done. You pay for the fix, not the guessing hours — and the printout is your defense against the upsell.
A $20 adapter turns your phone into a diagnostician — and the app earns its keep even when nothing's broken.
Plug a cheap Bluetooth OBD-II adapter into the port under your dash. When live data would settle the question, the app names exactly what to capture — per-cylinder misfires, fuel trims, a cold-start log — runs a short scan, and folds it into the case. Codes are the start, not the answer.
Enter your VIN and the app decodes it and checks open NHTSA recalls and factory campaigns. The Kia in the demo was a $6,800 engine the owner nearly paid for — covered by recall the whole time.
Nothing wrong today? Ask for a maintenance plan — what's due now and what's coming, grounded in your platform's known wear items and current mileage, not a generic checklist.
The latest build turns your phone into a running record of the vehicle, so the app earns its keep between problems, not only during them.
Log a drive and the app records live engine data in the background — RPM, temps, fuel trims, per-cylinder misfires — so the fault that never happens in the driveway gets caught in the act. Add a note days later and it pairs your “heard a rattle here” with the data from that exact moment.
Point your phone at the door-jamb barcode — the app reads it, check-digit-validates it, and decodes your exact vehicle and full spec sheet. No squinting at 17 characters.
Record what you’ve done — oil, brakes, transmission fluid — with the date and mileage, and keep a running service history per vehicle. Your maintenance plan reflects what you’ve actually done, not a generic checklist.
A one-tap branded vehicle report — health status, maintenance due, open recalls, recent drives — shareable as a PDF you can show or text to your mechanic. Walk in with the evidence already in hand.
Most "AI mechanic" apps sell you a dongle locked to their app and profit when you buy parts. RootCause does neither — which is what lets the don't-buy list stay honest.
No proprietary hardware, no bundled scanner locked to us. Plug in a standard adapter and reuse it with anything, anytime. We like the Veepeak OBDCheck BLE+ (~$22, our pick) or the OBDLink CX (~$80, premium) — both are BLE, which iPhone actually requires. The cheap classic-Bluetooth ELM327 clones won't pair with iOS at all.
No parts commission, ever. When a verdict names the fix and the part number, it's for price transparency — we make nothing on your repair, so "don't buy the head gasket" is advice you can trust.
The reasoning is measured against a bank of cases with dealer-confirmed answers — not marketing vibes. And every case you close teaches it what the shop actually found, so it keeps getting sharper about your exact platform.
Per-vehicle, no subscription surprise — your case history stays alive while your vehicle is active, and one avoided wrong repair pays for years. The iPhone app is in testing now, with a native Android version in the works. Early testers get in free.
Get notified at launch