Is the fuel-economy change based on repeated tank/trip measurements?
A repeatable measurement is more useful than a single dashboard reading.
CarFactBook Diagnostics V2.3
Start with what the car is doing.
Choose a symptom and, when possible, an exact vehicle code. Work through structured observations first, then compare them with reviewed owner evidence. CarFactBook does not invent a diagnosis or rank a failed part from unsupported anecdotes.
Symptom first
What are you seeing?
Electrical
Won't start / hard starting
Check reviewed reports for Nissan Dayz B45W.
ElectricalWarning light or message
Check reviewed reports for Nissan Dayz B45W.
CoolingOverheating / running hot
Check reviewed reports for Nissan Dayz B45W.
A/C / climateA/C not cold
Check reviewed reports for Nissan Dayz B45W.
Suspension / steeringVibration / shaking
Check reviewed reports for Nissan Dayz B45W.
BrakesBrake problem
Check reviewed reports for Nissan Dayz B45W.
Hybrid / EV systemHybrid-system problem
Check reviewed reports for Nissan Dayz B45W.
Fuel / emissionsPoor fuel economy
Check reviewed reports for Nissan Dayz B45W.
Choose an exact vehicle
Selected: Nissan Dayz B45W · 2019–2023
Structured checks
0/2 checkedWork through observations, not guesses
Did route, traffic, tyre pressure, load, climate use or driving pattern change?
Operating conditions can change consumption without proving a mechanical fault.
These checks organize observations and safety decisions. They are not a substitute for manufacturer service procedures or a qualified diagnosis, and CarFactBook does not assign a failed part without supporting evidence.
Diagnostic summary
Further evidence required. 0 of 2 observations recorded.
Answers stay on this page until you leave or change vehicle/symptom. Optional saving stores only this session on this browser, separate from Garage and Vehicle Passport. It is not uploaded or shared. Restore explicitly after returning to the same selection; references are refreshed from CarFactBook.
Preparing session summary…
After a mechanic checks the car
Close the loop with the actual diagnosis, repair, part, cost and outcome. The exact vehicle, symptom area and your diagnostic observations are prefilled, but you can edit them before submitting.
Choose an exact vehicle above to prepare a repair-outcome report.Reports remain pending until CarFactBook reviews them. A diagnostic session does not become a confirmed diagnosis automatically.Useful references for your exact car
These references relate to the selected symptom. They do not identify a faulty component or recommend replacing it. Confirm equipment, production period and source caveats for your individual car.
Verified facts
Fuel type →
Regular unleaded gasolineUse the manufacturer-specified fuel.
Nissan · Verified 2026-10-04
WLTC fuel economy — cited reference →
19.2 km/LOfficial test-cycle figure; real-world economy varies.
Nissan · Verified 2026-10-04
Reviewed repair evidence
0 related reportsPoor fuel economy
Reports are matched by related system category for Nissan Dayz B45W. Compare the recorded symptom and outcome; a repair on another car does not diagnose yours.
No reviewed match yet. CarFactBook will not manufacture a likely cause just to fill this screen. Check the exact vehicle facts or contribute a real repair outcome through Problems.