What we thought we bought
- A running silver Q50 Premium with a healthy 3.7L V6
- An intact exterior with factory wheels
- A usable interior needing nothing more than a deep clean
- An affordable first project with room in the budget for modifications
Project 001
The 2015 Q50
The Car That Started It All
Swap Complete · Inspection Passed Sept. 6 · Catalyst Monitor Incomplete
- Engine
- 3.7L V6
- Drivetrain
- RWD
- Odometer
- ~159K mi
- Source
- Bought at Auction
Project Summary
An affordable buy, on paper
A silver 2015 Infiniti Q50 Premium with roughly 159,000 miles looked like the ideal first project: rear-wheel drive, a 3.7L V6, and a price that made sense for a teenager's first real car.
The hammer said $2,900. The invoice said $4,168 once the auction fee, broker/service fee and document fee were added — before a trailer ever moved.
Then the mechanical unknowns landed. The car arrived filthy on a trailer, refused to shift past third gear, and started throwing lean codes on both banks — turning an affordable buy into a lesson in what a car actually costs after the bid. Two previous owners, Texas history and a last recorded reading of 155,546 miles in March 2026 came with it.
Where it stands today: the VR30 transmission swap is complete and the transmission is working, the earlier lean-code issue has been addressed, and the Q50 passed inspection on September 6, 2026. Catalyst-efficiency testing for P0420 / P0430 continues and the catalyst monitor is still incomplete, so nothing about the converters is being called fixed.
- Vehicle / Auction Invoice
- $4,168
- Transportation
- $631
- Taxes, Title & Registration
- $370.25 estimated
- Shop Transmission Estimate
- $7K–$8K
- VR30 Swap
- $2,900
Sale $2,900 + auction fee $898 + broker/service fee $295 + document fee $75
Confirmed — $613 Austin to McKinney + $18 McKinney to home
Expected at county tax office; inspection station charge not yet reconciled and excluded
Full replacement — declined
Work complete — public budget allowance for transmission, parts, labor and fluids; payment confirmation pending
The $4,168 figure is the vehicle-and-auction invoice total only — before transportation, taxes, title and registration, diagnosis, repairs and modifications. Source documents, personal details and account information stay private. Title, tax and registration figures are an estimate based on the $4,168 invoice amount and current Texas/Denton County fees. The county tax office determines the final taxable value and amount due.
The Gap
The listing and the reality were two different cars
What we actually bought
- A transmission that would not shift beyond third gear
- Burnt transmission fluid reported during diagnosis
- A full replacement recommendation estimated at $7,000–$8,000
- P0171 and P0174 lean codes on both banks at arrival, with no confirmed root cause at the time
- Transportation complications and a car that arrived covered in dirt
- A longer emissions story: catalyst testing for P0420 / P0430 is still under way
As Purchased
Exactly how it showed up
Nothing here has been cleaned up, staged or retouched. These are the auction-arrival photos — dirt included.
Before Us
Before us: the car's history
Before this Q50 became Project 001, it spent more than a decade on Texas roads. Its records show regular dealer service, several major repairs, earlier transmission work and a final front-damage report shortly before it reached auction. This is a plain-language summary of the history we reviewed — not a reproduction of the report.
- 2 previous owners
- Texas history
- 34 service records
- Personal lease, then personal ownership
- Last history-report mileage: 155,546
- No salvage, junk, rebuilt, fire, flood, hail or lemon title brand reported
- No odometer rollback indicated
- No airbag deployment reported
Key history — 6 of 24 records shown
- Feb 201646 mi
First owner recorded in Texas
Registered as a personal lease in Texas. Exterior recorded as silver.
- Jul 201959,485 miImportant
Internal transmission repaired
Internal transmission repair and transmission service, plus power-steering service, engine service and an oil and filter change.
- Jul 2023119,014 miImportant
Transmission fluid flushed
Transmission fluid flushed, four-wheel alignment, cabin filter and oil.
- Jun 2024132,001 miMajor service
A/C compressor and front struts replaced
A/C compressor replaced, front struts replaced, front and rear brake pads replaced, rotors resurfaced and A/C recharged.
- Mar 2026155,546 miMajor service
Radiator replaced
Radiator replaced and coolant flushed, plus air filter, oil, fluids and a tire inspection. This is the last mileage reading on the history report.
- Jul 22, 2026Damage reported
Front damage reported
A front-damage report was recorded shortly before the car reached auction.
The record does not describe severity or cause, and the arrival photos did not show obvious major front-end collision damage.
Issues & Diagnosis
What is known, what is still a theory
DrivetrainSwap complete
It would not shift past third gear
- Reported symptoms at arrival: harsh, delayed engagement and no shift beyond third gear.
- A diagnostic shop reported burnt transmission fluid and recommended a full transmission replacement estimated around $7,000–$8,000. That recommendation was declined.
- After research inside the Q50 community, the family chose a 2019+ VR30 transmission swap, published at $2,900 for transmission, parts, labor and fluids.
- The swap is complete and the Q50 has been picked up with the transmission working. The $2,900 shown publicly is the budget allowance for that work — payment confirmation is still pending.
Codes & DataAddressed · catalyst testing continues
P0171 and P0174 — both banks lean at arrival
- At arrival, both banks read lean — a symptom rather than a confirmed diagnosis at the time.
- That earlier lean-code issue has since been addressed. New engine air filters were installed as part of the maintenance pass.
- A separate chapter is still open: P0420 / P0430 catalyst-efficiency testing. Cataclean and additional drive cycles have been tried.
- The Q50 passed inspection on September 6, but the catalyst monitor is still incomplete. That is not the same as the catalytic converters being confirmed fixed, and title transfer and registration are not confirmed complete.
Other Codes & SymptomsReported / observed at arrival
P0500, P0720 and the way it actually drove
- P0500 and P0720 were also present, while the speedometer itself kept working.
- The car would not shift past third gear and ran at elevated RPM as a result.
- Slight engagement delay into drive and reverse, though shifts otherwise felt smooth.
- A post-rev RPM stutter/hang and an air-sucking sound at shutdown were also noted — both still unexplained.
Build Timeline
In the order it happened
- Step 01Complete
Auction research
Watching listings and setting a budget for an affordable first project car that a teenager could learn on.
- Step 02CompleteAugust 2026
Purchased at auction
The silver Q50 Premium was won largely sight-unseen. The vehicle-and-auction invoice totaled $4,168; source documents stay private.
- Step 03Complete
Transport and arrival
Delivered on an open trailer, still covered in dirt from the lot, with transportation adding real cost and complication.
- Step 04Complete
Codes and symptoms discovered
Once scanned and driven, the transmission behavior and the P0171 / P0174 lean codes surfaced.
- Step 05Complete
Shop diagnosis and $7K–$8K recommendation
A shop reported burnt transmission fluid and recommended a full replacement for roughly $7,000–$8,000.
- Step 06Complete
VR30 research and $2,900 swap decision
A 2019+ VR30 transmission swap became the chosen direction, published at $2,900 for transmission, parts, labor and fluids.
- Step 07Complete
VR30 transmission swap completed
The swap was carried out and the Q50 was picked up with the transmission working. The $2,900 figure remains a public budget allowance; payment confirmation is pending.
- Step 08Complete
Engine air filters installed and lean issue addressed
New engine air filters went in and the earlier P0171 / P0174 lean issue was addressed. The cabin filter and plate hardware are not confirmed installed.
- Step 09CompleteSeptember 6, 2026
Inspection passed
The Q50 passed inspection on September 6, 2026. Title transfer and registration are not confirmed complete.
- Step 10Current
Catalyst monitor and P0420 / P0430 testing
Cataclean and further drive cycles have been tried, but the catalyst monitor is still incomplete. Catalyst-efficiency testing continues.
- Step 11Planned
Roadworthy and reliability work
Fluids, maintenance items and real road testing before anything cosmetic happens.
- Step 12Planned
Appearance modifications
Black roof, mirror caps, grille and lower lips, with wheels considered later. Nothing installed yet.
Build Plan
Reliability first. Looks second.
Reliability First
- Transmission resolved — VR30 swap complete and shifting
- Complete the catalyst monitor and finish P0420 / P0430 testing
- Fluids and deferred maintenance
- Real road testing before any cosmetic work
Appearance Second
- Black roof
- Black mirror caps
- Black grille
- Black front lower lip and side lower lips
- Wheels and further modifications considered later
Content Along the Way
- Episodes documenting each stage
- Build-log write-ups with the actual data
- Cost updates as receipts are confirmed
- Lessons — including the mistakes
Items are marked as they are actually finished. Anything not called complete on this page is still planned or in progress.
Related Stories
The write-ups in progress
Diagnosis
The Shop Said It Needed a $7,000 Transmission
Coming soonTransmission
Why We Chose a VR30 Transmission Swap
Coming soonEngine & Codes
What P0171 and P0174 Actually Meant
Coming soonFees & Totals
The Auction Price Wasn't the Real Price
Read the entryFollow the car that started it all
Episodes, build-log entries and confirmed costs get published as the work actually happens.