The NCT checklist for your car.
Find out what yours actually fails on.

• Check every light on the outside of the carTurn the lights on and walk around it: dipped beam, full beam, side lights, tail lights, indicators front and rear, side repeaters, fog lights and the reverse light.
• Get someone to press the brake pedal while you watchAll three brake lights have to work, including the high one in the back window.
• Check the light over the number plateIt is the most forgotten bulb on the car and it fails the test on its own. Check both if your car has two.
• Make sure no warning lights stay onTurn the key and watch the dashboard. They should all light up, then go out once the engine is running. Anything still lit needs sorting before you go.
• Replace any blown bulbs before the testBulbs are €3 to €8 in any motor factors and most take about five minutes with no tools.

This is the single most common reason cars fail the NCT in Ireland, and the cheapest to rule out. Do it tonight in the driveway.

• Push down on each corner and watch it settlePress hard on the wing over each wheel and let go. It should settle in one or two movements — if it keeps bouncing, that shock absorber is worn.
• Listen for knocking as you turn the wheelWith the engine running, turn slowly from lock to lock. Knocking or clunking means a worn joint.
• Look underneath for split rubber bootsCheck the driveshaft and steering rack boots. A split one is a straight fail and it is easy to see.
• Drive over a speed bump with the windows downRattles and knocks are usually worn bushes or drop links, and both are cheap compared to shocks.

The bounce test takes thirty seconds and catches the most expensive thing on this list before you have paid for a test.

Shock absorbers: €200 to €400 a pair fitted. Drop links and bushes are far less.

• See whether the car pulls to one sideLoosen your grip on a flat, straight stretch of road. If it drifts, the alignment is out — and that is exactly what the side slip plate measures.
• Look at how the front tyres have wornStand in front of the car and look across the tread. More wear on the inner or outer edge than in the middle means the alignment is out.
• Make sure the tyres are at the right pressureThe figures are on the sticker inside the driver door. Wrong pressures throw the side slip reading on their own, so do this before paying anyone for alignment.
• Get the alignment done if any of that is trueThis is the one part you cannot do at home — it needs the gauges in a tyre shop. Most will do it while you wait.

Side slip fails about one Irish car in eight, and almost nobody checks it beforehand, because a car with the alignment out drives perfectly normally.

Wheel alignment: €30 to €50 at any tyre shop.

• Check the car brakes in a straight lineThe rollers measure each wheel separately, and most failures here are imbalance rather than weak brakes. A car that pulls left or right under hard braking will fail.
• Feel whether one wheel is running hotAfter a decent drive, a wheel much hotter than the others is a caliper that is not releasing. On the rollers it shows as one side working far harder.
• Test that the handbrake holds on a hillIt is measured too, and on many cars it is the half that fails. It should come up in three to six clicks and hold the car.
• Drive the car properly before the testIf it has sat unused for weeks, surface rust on the discs reads as poor braking. Twenty minutes on the road clears it.

If you fail here, bring the printed report to your mechanic. It gives the exact reading per wheel, which saves them the diagnosis.

• Check the tread is at least 1.6mm deepUse a tread gauge, which costs about €3 in any motor factors, and check across the full width of each tyre rather than just the middle. Anything under 1.6mm has to be replaced before the test.
• Look along each sidewall for cracks or bulgesA bulge is a dangerous fail on its own, and the tyre should not be driven on at all.
• Make sure both tyres on an axle matchSame size, type and tread pattern. A mismatched pair fails even with plenty of tread on both.
• Make sure the tyres are at the right pressureThe correct figures are on the sticker inside the driver door. Do the spare too if the car carries one.
• Check the spare, jack and wheel brace are thereOnly where the car was built with them — a car that came with a repair kit instead is fine.

Tyres wear from the inside edge first when the alignment is out, and that edge is the one you cannot see without turning the wheel to full lock. Turn it and look.

• Shine the headlights at a wall and compare themPark square on about five metres back with the dipped beams on. Neither beam should sit higher than the other or point up into the wall.
• Have the aim reset if you changed a bulb or headlightReplacing either usually moves the aim, and there is no way to put it back by eye.
• Clean up cloudy or yellowed headlightsHazy plastic throws away a lot of light and can fail on beam intensity. A restoration kit is €10 to €15 and takes about an hour.
• Make sure both headlights are the same colourOne newer bulb on its own often is not. Replace headlight bulbs in pairs.

You can spot a bad aim against a wall in two minutes, but correcting it needs the beam setter in a garage. It is one of the cheapest things on this page to have done.

Headlight aim adjustment: €20 to €30 at most garages.

• Listen for grinding or squealing when you brakeGrinding means the pad is gone and the disc is being cut. It only gets more expensive the longer it is left.
• Look at the brake discs through the wheelA pronounced ridge around the outer edge or heavy scoring means the disc needs replacing.
• Check the brake fluid level under the bonnetIt should sit between the two marks and look honey coloured rather than dark. A dropping level with no leak usually means the pads are worn.
• Press the brake pedal hard while parkedIt should feel solid and stay where you put it, not sink slowly towards the floor.
• Look behind the wheels for leaks or rusted linesDamp patches around the brakes or corrosion on the pipes underneath will fail.

A pedal that sinks slowly to the floor is not an NCT problem, it is a do-not-drive problem. Get it looked at before you go anywhere.

Pads and discs: €150 to €300 per axle.

• Pull out every seatbelt and give it a sharp tugLook along each one for fraying or cuts, and check it locks when you jerk it. Every buckle has to click in and release.
• Run the wipers on a wet screenStreaks, judder or a torn blade all fail. A new pair is €10 to €20 and they clip on in a couple of minutes.
• Top up the washer bottle and test the jetsThe water has to actually reach the screen rather than going over the roof.
• Look for chips or cracks in front of the driverDamage bigger than a €2 coin in the area the wipers sweep in front of you is a fail.
• Sound the horn and check the mirrorsEvery mirror has to be secure and unbroken, and the horn has to work.

This whole area is fifteen minutes and a few euro, and it fails about one car in twelve. There is no reason to lose a test on it.

• Do the bounce test at home firstThe test rig shakes each wheel and measures how much movement the shock absorber soaks up. A corner that keeps bouncing in the driveway will read badly on the rig, and there is no way to fake it on the day.
• Look for oil running down the shock absorbersAn oily film on the body of the shock means the seal has gone. Check all four.
• Expect to replace shocks in pairsThe test fails a side-to-side imbalance even when both sides are within the limit, so doing one is usually money wasted.

Worn shocks are why the car feels floaty on a motorway as well as why it fails here. It is a comfort and safety fix, not just a test fix.

Shock absorbers: €200 to €400 a pair fitted.

• Start the car cold and look at the exhaustBlue smoke is burning oil, black is running rich, and thick white on a warm day can mean a head gasket.
• Listen underneath for a blowing exhaustA hole is usually louder at the front of the system than at the tailpipe.
• Check the ground where the car has been parkedFresh oil, coolant or fuel underneath is a fail.
• Look under the bonnet for anything looseEngine mounts have to be secure, and no pipes or wiring should be rubbing against anything.

A blowing exhaust often fails on noise before it fails on emissions, and replacing one section is among the cheaper garage jobs.

• Look along the sills under the doorsCheck the floor pan and subframe mounts as well. This is where structural rust shows up first on Irish cars.
• Tap any suspect metal and listenSound metal rings. If it sounds dull, or a screwdriver goes through it, it needs welding.
• Open and close every door, the bonnet and the bootAll of them have to latch properly and stay shut.
• Feel around for sharp edgesAccident damage or corrosion that leaves an edge a pedestrian could catch on will fail.
• Check nothing is hanging underneathExhaust sections and underbody trim have to be properly secured.

Surface rust on a panel is not a fail. Rust that has gone through structural metal is, and underseal sprayed on the week before changes nothing.

A small structural weld: €50 to €150. Extensive sill or floor work runs well past €500.

• Get the engine management light sorted firstOn most cars a lit light fails the test before the probe goes near the exhaust. Have the fault read before you book rather than after.
• Drive for twenty minutes before you arriveThe engine has to be fully warm for the reading to be fair. A cold engine will not read well.
• Diesels: take it for a long run the day beforeSustained revs on a motorway help burn the DPF clean. A diesel used only for short journeys is the classic emissions failure.
• Petrols: change the oil if it is due anywayFumes from the crankcase end up in the reading, so old oil genuinely costs you here.
• Tap the catalytic converter and listenA rattle means the internals have broken up, and it has to be there in the first place.

Never sit idling in the queue with a cold engine. Arrive having driven the car, not having crawled the last two kilometres.

A diagnostic scan to find out why the light is on: €50 to €80, and worth it before the test rather than after.