Your Questions Answered

The questions and answers in this section of relate to previous versions of the MOT manual and should not be relied on, as the law may have changed. Please ensure you check the relevant section of the current MOT manual, which can be found on this site.

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Exhaust fixing

Q Will my car pass its MOT based on my exhaust being clamped to the manifold header instead of being originally bolted The exhaust studs rounded..

Name: John   Town: Gateshead

The overall security of the exhaust system should be assessed. one or more exhaust mountings missing may not be a Reason for Rejection a reason for rejection An exhaust system not adequately supported if your exhaust is soundly supported it should pass

exhaust bracket

Q My exhaust rear tail pipe bracket has cracked I have secured it with copper wire as apart from that there is nothing wrong with the exhaust Will this cause my car to fail its MOT thank you

Name: M. Routledge   Town: Ashington

The manual states The overall security of the exhaust system should be assessed; one or more exhaust mountings missing may not be a Reason for Rejection the reason for failure is An exhaust system not adequately supported if yours is well secured a reasonable tester should pass it to be on the safe side you can call the test centre and ask them they will normally tell you their policy which can vary from test centre to test centre


Q Will I fail an MOT if I have an aftermarket backbox for my exhaust

Name: Brandon Crawford

Not in itself, however if it causes any of the following issues, the vehicle will fail:

1. The exhaust system is not adequately supported.
2. There is a major leak of exhaust gases from any part of the system.
3. A catalytic converter or particulate filter is missing where one was fitted as standard.
4. A silencer is in such condition, or of such a type, that the noise emitted from the vehicle is clearly unreasonably above the level expected from a similar vehicle with a standard silencer in average condition.
5. Exhaust fumes entering the drivers or passenger area.

exhaust tailpipe missing

Q hi

would a exhaust tailpipe missing fail an mot

Name: mark

As long as it does not effect the function of the exhaust and that the exhaust gases would not dangerously heat part of the vehicle. Dont forget that the petrol tank is usually located at the rear of the car also. If the exhaust gases where to heat this area then it could be considered dangerous

Minor exhaust leak

Q Rear Exhaust has a minor leak of exhaust gases 7.1.2

Name: Barry

Minor exhaust leaks are no longer an MOT fail

Centre exhaust box is corroded

Q The last 2 MOT on this car I am considering buying says the centre exhaust box is corroded on the advisory notes.

Can you explain what this is please x

Name: Jo Gregory

Exhausts only fail the MOT for a major leak. Obviously a minor leak or corrosion would be pointed out as a possible future problem but at the time of the MOT test it was not bad enough to fail the MOT. I would look at the car with the premise that it may need a new exhaust soon.

Exhaust leak

Q Would a gas analyser test/emissions test on an exhaust system show/fail if there was a leak on an exhaust

Reason my car failed its MOT on the 19th September due to a leaking flexi pipe towards the front under the handbrake/gear stick....this was repaired on the 20th September

But the garage have left an MOT exhaust emisions test result receipt completed on the 19th stating overall result...PASS....

If a system is leaking would it not fail an emissions test

Have I been charged 230 for a part I didnt need

Name: Mark

A small leak is no longer an MOT fail. Unless the inspector thought that the gases would dangerously enter the passenger compartment.

Front exhaust mount is broken

Q The front exhaust mount is broken on my Peugeot 207. will it fail the mot they said a new centre section and clamps is required on the advisory notes of my service.

Name: K. Rea

The exhaust does not need every bracket as long as the tester deems it secure. one or more exhaust mountings missing may not be a Reason for Rejection

Flexi Pipe repair

Q small leak from flexi pipe has been repaired with exhaust cement it was advisory on mot feb 17will this affect next years mot

Name: brian   Town: edinburgh

It would depend on which flexi pipe you are talking about. If it is part of the exhaust system then as long as the exhaust does not leak it should pass

Q My Audi A6 has just failed an MOT, down to code 7.1.2
I have an injector which is weeping oil / diesel onto the exhaust manifold, where it is burning off and causing a smell. This is not a release of exhaust gases, nor an emission so how can it be an MOT failure

Name: Ed   Town: Hull

Code 7.1.2 would be due to an exhaust leak so if you are unhappy with your MOT test you can appeal at but You need to discuss your test results with the test centre before anyone starts repairs.

Exhaust mounting

Q My exhaust is tied up with two wires is is a mot fait the exhaust system on gasses is fine its just the mounting

Name: David   Town: Sheffield

Providing the tester thinks that the exhaust is secure and not likely to come adrift you will pass

Rusty Exhaust

Q if the exhaust is rusty but no leaks is this ok for a mot test

Name: colin fox   Town: ammanford

The vehicle will not fail with a rusty exhaust as long as no gasses can excape and the exhaust is complete

Exhaust clamp

Q I have a Peugeot 207 and its failed the mot on a rear clamp that has deteriorated to the point where it is split apart, there are 3 clamps holding the exhaust up and it is secure but they failed it, does he have a right to fail it

Name: Jamie Riley

If he deems that the exhaust is not adequately supported

No Back Box

Q Are you required to have a back box for an mot and is there a set db noise for either the mot or what is legal for police

Name: josh m   Town: wakefield

Regulation 542 of the Road Vehicles Construction and Use Regulation 1986 as amended: Every exhaust system and silencer shall be maintained in good and efficient working order and shall not be altered to increase the noise made by the escape of exhaust gases. This also means that if the car was fitted as standard with a back box then it needs one to pas the MOT

Exhaust leak

Q My Honda Element has a corroded and broken flange where the back box meets the tail pipe. As it is an import it seems I cant get a replacement easily. I have wired it together temporarily. Would this fail

Thank you

Name: Mike   Town: Brighton

Small exhaust leaks are no longer an automatic fail unless the gases are deemed hazardous i.e. enter the passenger compartment. All parts of the exhaust must still be secure.

Advisory notices

Q I am going to see a car and I have just checked the MOT history. I know nothing about cars, other than they either move... or dont.

When I check the MOT It passed, I see that there are two issues:

Test date 11 January 2017

Expiry date10 January 2018

Test Result Pass

Odometer reading 63,240 miles

MOT test number 5857 0071 1330

Advisory notice items

Exhaust has a minor leak of exhaust gases BACK BOX 7.1.2

Oil leak

What do the Advisory notice items mean Are they serious The car in question is a PEUGEOT 107 and is selling for 2000.

Name: Richard   Town: CAMBRIDGE

Advisory notices are to inform you of defects that could become more serious but are not at the time an MOT failure.

Exhaust leak

Q front exhaust has a minor leak of exhaust gasses will it pass mot this year


The car would only fail for a major leak.

Q I have seen legislation for car manufacturers that limits petrol cars to 75 do NSA diesel to 76, it also requires government to monitor levels. It seems to me the only government can monitor is via MOT therefore I disagree with the answer that there is no limit, only inspector deciding reasonable.

I live beside a road regularly used as a race track late at night and certainly from the noises ai hear, dump valves etc this is not 76 dab or reasonable by any stretch of the imagination.

Surely it is time that mot included a d noise level test to clarify this whole area once and for all

Name: G Derby   Town: Banbridge

I agree with you about the noise levels. Some motorbikes especially seem to be very loud. The noise level of an exhaust is only a failure if it is deemed excessive and/or louder than that of a comparable vehicle. The main reason for exhaust tests is emissions and major leaks. A turbo dump valve is not tested for noise levels during an MOT test

Exhaust problem

Q My exhaust has the smallest hole that sprays a little will it still pass

Name: Matt   Town: Alton

Providing the emission is within the required limits and there is no unreasonable sound coming from the exhaust it will pass

MOT Disputed

Q We bought our 2002 motorhome from a dealer in april 2016 and picked it up on the 2nd june 2016 its mot was done in may 2016 with no advisories. We have had many problems and have had 2 separate independent reports done the first states that the front to rear brake pipe is heavily corroded, both front wheel arches are corroded and holed near to spring mounting,OSR brake pipe is corroded and exhaust rubber mounting broken backed up with digital photos. The second report states front to rear brake pipe dangerous, exhaust mounts corroded and missing. Should this have passed its mot in may and at the least should it have had advisories about the brake pipes etc. We had only had it 12 weeks when we found this out. I know its not part of the mot but there is also excessive rot to the outer floor and sides of the caravan part of the motorhome. All the dealer said over the phone was he needed it back to look at but wasnt willing to collect it. Weve now sent a letter and reports and photos but the dealer has not responded.

Name: Bobby   Town: Leeds

There is an official online complaint form that you can use

Click here for more information

Minor Exhaust Leak

Q front Exhaust has a minor leak of exhaust gases 7.1.2

How much to fix

Name: Wade   Town: Dulwich

The person fixing the leak will have to insect it first to give you a price most garages can provide this service

MOT Advisories

Q Hello,

Im trying to work out how much my MOT will cost in a few months; the car has some advisories, such as:

exhaust has a minor leek of exhaust gases 7.1.2, nearside rear brake hose has slight corrosion to ferrules 3.6.B.4e, offside front brake hose has slight corrosion to ferrules 3.6.B.4e and finally corrosion forming on rear axle and front bottom arms.

My car is a 2001 K reg vauxhall corsa comfort in royal blue.

As a lot of the advisories are due to corrosion, I was just wondering if there is anything I can do to stop or help reduce the corrosion problem.

I understand it is near enough impossible to predict the exact cost of my MOT, but going on what advisories I have, just an estimate for those would be fantastic.

Thank you.

Name: Lucy Southgate   Town: Gloucestershire

It is not possible to say what the costs can be if there is little or no deterioration in the components then they could possibly pass again this year a inspection by a competent mechanic should give you some sound advice

Q Can a car fail mot with an exhaust cracked manifold

Name: Zoe grant   Town: Hfd

The manual states that a failure is only due to a major leak of exhaust gases from any part of the system it is usually down to the testers judgement but a phone call to a test centre will usually give you an indication as to their policy

Scooter Exhaust

Q On my scooter the exhaust is quite rusty. will it still pass its M.O.T

Name: Tom Bingley   Town: Carnforth

As long as there is no holes in the exhaust that will make the emissions test fail or it is deemed dangerous then it will pass

EGR Valve

Q My EGR Valves are faulty in my Range Rover Sport. I am being advised to fit blanking plates but this will cause the Engine Management Light to remain on permanently. Will this fail the MOT in 2018

Name: Robert

An engine management light will not fail an MOT. The only thing that might be affected is your emissions but this is actually unlikely. An EGR reruns the exhaust gasses though the inlet manifold at certain rev ranges to make sure that all the fuel is burnt. At present its failure or removal is not an MOT fail, as long as the MOT tester doesnt deem it an illegal modification, as the main concern is with diesel particulates and not the NO2 which the EGR is designed to reduce. It would be a jobsworth MOT tester that would fail it

Motorbike Exhaust

Q I was wounding if my motorbike would pass its mot has it got a sport exhaust just didnt know if they would fail it for being to loud

Name: andrew sheffield

Construction and use regulations say that a pipe should not be altered in any way to increase noise, and should clearly and indelibly be marked with either the British standard marking indicating that it has been tested in accordance with test 2; or ii a reference to its make and type specified by the manufacturer of the vehicle.

Exhaust cracked

Q I recently took my car for a service. And they said my car need a new middle pipe and back box exh. I think they are cracked. Would this make my car fail its mot

Name: Emily Perry

If the exhaust was leaking badly or in danger of falling off then yes, the car would fail

Detatched exhaust bracket

Q Detatched exhaust bracket, no support for catalytic converter and it is free to bounce around and knock on the cross member, also flexible webbing around the cat has come adrift ,is this an MOT failure

Name: S.foster   Town: Birmingham

Yes - The entire system must be securely fixed to the vehicle as intended or it will fail.

broken exhaust clamp

Q Can one broken exhaust clamp on a car fail its m.o.t

Name: Shaun   Town: Hastings

Yes - The entire system must be securely fixed to the vehicle as intended or it will fail.

Hole in pipe leading to back box

Q Hole in pipe leading to back box would this fail an mot

Name: Jack walker   Town: Stranraer

Exhaust holes have to be deemed serious to fail the MOT. A small hole will not fail unless the gases go into the passenger compartment

Motorbike Footpegs

Q Do you need both rear footpegs for motorcycle not as I have 2rear exhaust pipes on top of each other and the top one is for cosmetic purposes only and one peg on other side only

Name: tony   Town: basingstoke

If you have a seat capable of taking a pillion passenger then it must have footrests for this passenger. You could get a cowling to go over the rear of the seat to negate this but Ive heard a lot of stories of MOT test stations overlooking this issue.

Projecting exhaust

Q exhust projects to the pedestrian side of car is this a mot failure

Name: Allan Williamson   Town: Canvey Island

If the exhaust is deemed dangerous to the public Hot surface of protruding sharp edge then the vehicle will fail.

Failed CAT

Q Hi had an mot done it states pass on its exhaust emissions test but 5 days later the engine warning light came on as it needed a new cat converter. Why would this not have been picked up Thanks

Name: Anonymous   Town: Derby

Because the MOT test only tests the car at the time of the MOT. It does not predict future failures. Parts can fail at any time. If the Cat was ok at the time of the test then the car will pass


Q My year 99 petrol/LPG car always runs on LPG.

should this be tested as a BET test

Cat test to default limits

or cat test to specific limits

there seems to be some un certainty

thank you

Name: Stuart   Town: Trowbridge

The car will tested for which ever fuel the car is running on when presented for the MOT test

LPG vehicles: the hydrocarbons emitted are propane rather than hexane. So the HC reading obtained must be divided by the propane/hexane equivalency factor PEF marked on the gas analyser. For example: An LPG vehicle gives a reading of 700 ppm. The PEF marked on the machine is 0.48. So the actual MOT value is: 700 0.48 = 1458 i.e. fail

Some exhaust gas analysers have an automatic facility for doing this

CO Under 3.5

HC under 1200 ppm

MOT Exhaust

Q I have a exhaust manifold on my car which doesnt have precats, but I have a sports catalytic converter, will it pass a MOT

Name: Ed   Town: Herts

If the car was not originally fitted with a catalytic converter you only need to pass the emission test

Emission warning ligh

Q I have a warning light stating emissions workshop and believe there is hole in the exhaust will it pass the mot

Name: Jo douglas    Town: Essex

The car will be tested for emissions the warning light is not part of the test and can come on for a number of reasons it is advisable to get it checked

Emissions not picked up

Q Exhaust emissions not picked up on gas tester Advisory info. what that even means

Name: Sim   Town: Wakefield

This means that the emissions were so low that the equipment could not get a reading so you were passed with an advisory

Mot Query

Q Bought a 07 Hyundai 8mths ago 2016 with a years mot, just discovered that breaks have failed on me plus exhaust is hanging off.

Also looked online at Mot history and it failed back in 2011for a fault with the breaking system.

Could this still be the issue and would the Mot I had picked it up.

I feel that the garage I bought it from have ignored the issues and passed a fake Mot

Name: Berni   Town: Cardiff

With the car being tested 8 months ago you would have no comeback on the tester it would be very unlikely that these problems would have been obvious with the age of the car unless it was in pristine condition when you bought it most of these faults could be expected

Scooter emissions

Q I have a 50CT pulse speedlight 2 but am lil worried to take it for a mot because its smoking a lil out of the exhaust system will it still pass

Name: Mikey cartwright   Town: Halifax

Currently not tested

Exhaust Query

Q 125 exhaust has a small hole in it by the baffel, will it pass

Name: Sean   Town: Newtown

This will be a matter of the testers judgement if it does not effect the sound or emissions then it will pass but without seeing it cannot give a definite answer




It is complicated but all the details are at

Mot Emissions

Q What emissions MUST be measured when MOT testing a diesel car registered in 2012

Name: Philip Mason   Town: Cheltenham

Emissions are quite complicated DVSA have produced a PDF at

which gives all the information regarding emissions this will not take into account the current controversy with VW

Catalytic converter

Q Hello,

My mot is expiring at 12 August 2015.I booked mot test on 29/8 as we need the car to go on holidays on 25/7.The car failed.We fixed what they asked and we booked for another mot test on 13/7.We failed again at exhaust emissions with CO 0.756.They told us that we need to change the catalyt converter.What do you think I can altelnative do as it will cost a lot of money

Kind regards,


Name: Matthildi   Town: Southampton

The net has loads of offers on cats some research online you should be able to pick one up for sensible money

Manual Codes

Q Ive just had my M.O.T done and in the advisory items information panel there are numbers in brackets after the advisory items ie 7.1.2 What do these numbers mean

Name: Nick   Town: Eye

If you go to the manual section you will see that all components are numbered 7.1.2 would refer to the exhaust system


Q my vw sharan exhaust heatshield looked like an aluminium baking tray was taken off by garage as it was dangling about, will this effect my next mot.

Name: bill   Town: lincolnshire

providing the car passes the emission test and there is no excessive noise you will pass

Modified 125 cc Bike

Q If I modify a 125cc bike, with a 170cc bore kit or exhaust upgraded jets etc will it fail an MOT because its registered as a 125

Name: luke   Town: morecambe

If you change the capacity you need to have a full motorcycle licence and change details on your reg docs

non standard exhaust

Q hi, im taking bike for an mot and i has a none standard race exhaust fitted wil it pass an mot with this fitted or will the original have to be refitted

Name: calvin cooper   Town: swansea

As long as the tester does not think it too noisy it will pass

Advisory notices

Q hello.

my car failed its mot exhaust had hole one blown bulb

I removed car from st and had repairs carried out returning car to MOT St later that day for retest

Retest was scheduled for next day at 11 I booked in at 10.45 and waited around.

when my car was presented back to me with its MOT Cert I noticed it had an extra 3 advisories on it from when it failed day before one of the extra advisory was my temp gauge doesnt operate correctly as far as i understood this would be a mechanical issue rather than an safety issue perhaps I am wrong

basically, all I wanted to know is should extra things be added on a retest can some one explain the procedure.

One confused Golf Driver

Name: Klare   Town: Sussex

When the car was re submitted for the retest it was probably tested by a different tester it is a matter of personal assessment on the condition of components this was probably the reason for the advisory notices these can be very helpful

New Front Exhaust

Q will my car pass the emissions test if it has a new exhaust system as front

Name: katie   Town: redditch

Will not effect the emissions

Exhaust Noise Levels

Q Is there a set pass/fail dB level for motorcycle exhausts

Name: Albert Rapacioli   Town: London

No there is not dB levels recorded. it just has to be reasonable noise level expected from a vehicle

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