Tough and simple, but one failure can total the truck: the radiator leaking coolant into the transmission. Check the trans fluid first, always.
The 4.0 V6 Frontier is a no-nonsense work truck, but it carries a notorious design flaw where the transmission cooler is inside the radiator. When the barrier fails, coolant mixes into the transmission and destroys it — a failure so common it has a nickname. We check for it before anything else.
A failed internal cooler lets coolant into the transmission and ruins it, often called the strawberry milkshake of death.
CHECK Pull the transmission dipstick and look for pink, milky, or contaminated fluid — a deal-killer if present.
The VQ40 can develop timing-chain rattle as guides wear.
CHECK Listen for a rattle on cold start that may quiet with oil pressure.
Manifolds and cats fail on higher-mile trucks.
CHECK Listen for exhaust leaks and scan for catalyst-efficiency codes.
The fuel gauge sender reads inaccurately.
CHECK Confirm the fuel gauge tracks correctly.
Bidirectional OBD-II scan tool · Paint depth gauge · Tire tread depth gauge & DOT date decoder · Brake pad & rotor calipers / measurement tools · Battery & charging system tester · Compression and cylinder leak-down testers · Digital borescope · Floor jack and jack stands …
See the full Pre-Purchase Vehicle Inspection tool kit →
Pre-tagged for the Nissan Frontier (2005–2019).