Why a flooded car is a long-term problem

Modern cars have many control units, sensors and wiring connectors below seat level. Water that gets in makes the copper contacts corrode green from the inside. They do not fail right away, but they start acting up one by one over the following months or years.

What follows is warning lights that come and go, power windows that work only sometimes, an air conditioner that smells, and, most dangerous of all, airbags and ABS brakes that may not work on the day you need them.

10 things to check

• Smell inside the cabin. Close the doors and windows for a while, then get in and breathe. A damp, musty smell is very hard to get rid of. If the car has been sprayed with unusually strong air freshener, be suspicious.
• Seat rails and seat bolts. Look under the front seats. This metal is not rust-proofed. If the whole rail is rusty on a car that is not very old, it has probably sat in water.
• Under the carpet. Ask to lift a corner of the carpet. Look for dried mud, water marks, or carpet that looks newer than the rest of the car.
• Seatbelts. Pull each belt all the way out. The end that normally stays rolled up inside will have water stains or a mud line if the car was submerged. Cleaners often forget this spot.
• Spare tire well. Lift the trunk floor and look for standing-water marks, rust and mud in the well.
• Headlights and taillights. Look for fogging, droplets or water lines inside the lamp housing.
• Fuse box and wiring connectors. Open the fuse box cover inside the cabin and look for green or white deposits on the metal contacts.
• Under the dashboard and around the pedals. Shine a light up at the metal frame inside. Rust here does not come from normal use.
• Engine oil and transmission fluid. Pull the dipstick. If the oil looks cloudy, like milk tea, there is water in it.
• Every electrical button. Try every window, the door locks, interior lights, the audio system, wipers, and every air-con setting. Note anything that is slow or works only sometimes.

Warning signs in the paperwork and in what the seller says

• A price far below market with no clear reason.
• The car comes from an area that recently had major flooding. Check the province of registration in the registration book (lem tabien) and ask where the car was parked at that time.
• Brand-new seats, carpets or door panels in a car where everything else looks old.
• The seller will not let you take the car to a garage for inspection, or pushes you to decide quickly.

Ask directly whether the car has ever been flooded, and ask for the sale contract to state in writing that it has never been submerged. A confident seller will have no problem with that sentence.

If in doubt, pay for an inspection or walk away

A garage or used-car inspection center can lift the car to look underneath and open up places an ordinary buyer cannot reach. The inspection costs a few thousand baht, compared with chasing electrical faults that never end.

A car that has been flooded up to seat level is not worth any price, because you cannot estimate the repair bills in advance and it is very hard to resell. If you find several of the signs above at once, walking away is the right decision. This website does not inspect the cars in its listings. Buyers must inspect every car themselves.

For the rest of the checklist, continue with what to check when inspecting a used car before you buy.