Car Red Flags to Watch Out For

By Angela Monroe - August 5, 2020

Car Red Flags to Watch Out For

Red flags for cars can save you money and stress… if you can see them. Red flags for cars pre-warn drivers when to get a service, prevent accidents and help buyers spot lemons.

In this article, we go over a few red flags for cars and also list some common misconceptions.



More common on older cars but also on unrepaired scratches. Rust on the frame or chassis of the vehicle is much more serious and means the car is basically rotting away. Depending on the location, rust can be extremely time consuming and expensive to repair. Furthermore, if it’s in hidden locations, it can spread without detection until it’s too late. Excessive rust is a reason for writing off a vehicle.

Uneven Panel Gaps

new car panels

Panel gaps are the small gaps where the outside painted panels on a car meet. For example, where the doors meet the body or where the bumper bar meets the side panels. The gaps should be even and straight – the same small distance between panels is even along the whole gap. If these are uneven, ie; one end of a gap is noticeably wider than the other end, it can indicate the chassis is not straight.

This is because the parts of the vehicle body that attach to the painted panels don’t line up as they did when the car left the factory. Uneven panel gaps are an indication of previous serious accidents.

Check Engine Light

gauge cluster

One of the classic red flags for cars. The check engine light in the gauge cluster is a pretty general red flag and is usually asking for a diagnostics check. This means plugging the car into a diagnostics tool in order to see the fault codes it displays. These fault codes indicate what’s wrong. Some can be a quick fix and some can be much more serious – and expensive.

Engine Knock

Engine Knock

‘Pinging’ or ‘detonation’ means the air / fuel mixture in the cylinders combusts without being ignited by the spark plug as it should. The spark plug fires at a predetermined precise time so uncontrolled ignition in a cylinder can cause problems. The red flag is a metallic ‘pinging’ or ‘knocking’ sound audible from the engine. The common cause deposits on cylinder walls from poor quality, dirty fuel or worn or incorrect spark plugs. In some cases, knock can cause serious damage to an engine.

‘Milkshake’ Oil / White Smoke

Milkshake Oil White Smoke

This is often a telltale sign of a blown head gasket. A head gasket’s job is an important one. They create a seal between the engine block that holds the cylinders and the cylinder head that holds the valves and spark plugs. They prevent oil and coolant from leaking into the engine. The red flags are a milky colouration in the oil (milkshake oil) and/or excessive white smoke from the exhaust. 



This one is really for potential buyers. A Personal Properties Security Register (PPSR) document is easily obtained online. These documents contain critical information regarding a vehicle’s history such as if there is finance owing and if it’s ever been written off or reported stolen. 

Things that aren’t necessarily ‘red flags’…

Faded Headlights

faded headlight

You may have seen a yellowish discolouration on the headlights of some cars. This is UV damage caused by sun exposure. It looks disgusting and heavy UV damage can reduce visibility at night but it’s an easy fix. There are headlight restoration kits available, however, some can be repaired with a polishing compound. Some motorists even repair faded headlights with general household metal or furniture polish.

(Some) Lights Not Working

bmw lights

Of course, this is dangerous, especially at night and needs immediate fixing. That said, often the culprit is a blown fuse or bulb and can be easily and cheaply remedied. Check your owner’s manual for the fuse box location and diagram showing which fuses are for which circuit. These can be fixed for a few dollars in a few minutes.

Fan Belt Squeal

Fan Belt Squeal

The red flag here is the awful, high-pitched squeal. You may have heard this when a car is cold or started first thing in the morning. Fan belt squeal occurs when the belts in the engine slip on the pulleys they’re connected to. This can be caused by misaligned tensioners, poor installation, contamination or simple wear and tear. The good news is that there are simple fixes, for example, a belt squeal eliminator that you simply spray on. A more thorough fix is a trip to your mechanic – more expensive but still a quick fix.

Clear Coat Scratches

polishing car

These look pretty bad, especially on dark-coloured paint, but are repairable. Often they are caused by brushing past plants or when loading/unloading luggage. A clear coat scratch is usually light/white in colour and can be identified if they disappear when wet and reappear when dry. These scratches can often be buffed or polished out as they are only in the topcoat (clear coat) of the paint. 

End of the Day

man smiling in car

If you’re unsure of any red flags, it may be worth paying a professional to inspect your vehicle or one you’re thinking of purchasing. Keeping your car well maintained and giving it a good spring clean can save you big dollars down the track, especially if you pay attention to any red flags for cars.

Angela Monroe
Angela Monroe is the Community Manager at The Positive Group, specialising in giving people the information that they need when they need it, and putting you on the path to a fair financial future. She has 8 years of experience in helping Australians find the right finance solutions, and regularly contributes articles to empower Australians with the knowledge they need to become financially healthy.


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