# What Does It Mean



## Roger (May 17, 2003)

Would appreciate some advice from guys with more car knowledge than me....

I have a Golf 1.9 TDI which (probably fortunately ) is still under makers warranty.

This morning a waring light display came up and the "computer" diplay came up "Emission"

Any idea what it means...handbook seems to indicate an exhaust fault.

Is it going to harm the car to drive it for a while before getting it looked at.

Cheers

Roger


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## rhaythorne (Jan 12, 2004)

On a petrol car I'd think it means one or more of the numerous exhaust sensors is trying to tell you that something is wrong with the exhaust system, or the sensor(s) are at fault, or that maybe the catalytic converter is damaged. Not sure what it means on a diesel car though. I assume the TDI is a diesel?









I would doubt there's a probelm in continuing to drive the car unless you get pulled up by some roadside govt. stormtroopers testing for excessive emissions.

PG will no doubt know more far more than I do?


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## johnbaz (Jan 30, 2005)

hello roger

on the exhaust, forward of the catalytic converter is a lambda sensor (oxygen sensor), this monitors the amount of oxygen in the burned fuel and adjusts the fuel/air ratio accordingly, this could have gone tits up, i'm fairly certain that diesel engines have them now, as well as petrol









when i enquired about one for my old veccie, i was quoted Â£96- i made do with the old one
















hope you get it sorted.

regards, john.


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## pg tips (May 16, 2003)

If it's the orange light with an engine picture or a coil picture it's the engine management warning.

It says emmisions in the hand book but that doesn't mean that it is an emmisions fault that is wrong with it, it's just the engine management has picked up a reading from a sensor it doesn't recognise. It could be a number of things from a coolant sensor for example up to a fault in the ecu, normally it's a bad connection or a sensor somewhere has got a rouge reading, the dealer can clear the codes and reset it and it'll probably be fine, just like when you re boot your pc after it locks up.

General rule of thumb with orange light (as opposed to red lights where red means stop immediatley) if they are on permanently and the car is running OK it's still OK to drive with a little extra care and get it to the dealer for a check up when you can, the sooner the better but there really isn't any urgancy.

If the car *isn't* running OK it may be a serious fault, do not drive it any futher than is absolutly necessary.

If the orange light is flashing (esp if it's a new ford) don't drive, it most likely wont drive anyway if it's a new ford because the pump is probably faulty.

The AA can read most faults these days although legislation only requires the manufacturer to give out info related to emmisions so not all codes can be read and some manufactures block codes except to their own dealers. Funnily Rover wired their EOBD plug in wrong and no one could read them not even Rover til an adapter was made









Some strange ones you can get include an O2 sensor fault on the diagnostics actually being a misfire, think about it if it's misfiring not all the fuel is being burnt, therefore more than the expected level of oxygen will reach the sensor and you'll get an O2 sensor reading too high code,

One I came across which took a dealer a month to work out was a sensor fault code for the 2nd O2 sensor which they replaced twice, still the same, turned out to be a tiny hole in the exhaust just after the 1st O2 sensor (not all cars are fitted with 2 those that are are before and after of the cat) allowing some gas to escape thus the second sensor wasn't getting what it was expecting!

The real balls ache comes when the car is obviously not running right and the light hasn't come on and the diag comes up with no fault codes storred, on a modern engine it can be a right pain trying to find what might be wrong when the computer hasn't a clue!

btw all this engine management started in california due to the SMOG problem so for once British Rail can't be blamed!


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## Roger (May 17, 2003)

Thanks Guys...its all helpful.

PG,

Its a little picture of an engine (yellow/orange) and its on solid with no flashing. Seems to run Ok, I didnt notice any misfire or lack of performance.

I will get it to the Dealer ASAP.

regards

Roger


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## pg tips (May 16, 2003)

You should be OK to drive it then Roger.


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## Roger (May 17, 2003)

Thanks again everyone for the info

Roger


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## rhaythorne (Jan 12, 2004)

Just a quick thread hijack now that Rog is sorted!

PG, or anyone, what would you consider to be a "normal" front/rear brake balance on the average road car? Apparently lots of Renault Clio 172 Cups have failed their first MOT's because the rear brakes don't appear to be working, for reasons I wont bore you with. Of course they are working, but it seems that garages who understand the car pass them for MOT purposes whilst those that don't, fail them. The brake balance is something like 90% front / 10% rear. Quite extreme!

Any comments?


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## pg tips (May 16, 2003)

I'm sure when I was training all those years ago the approximation of 80 / 20 was used.

I went to a guy the other day with a 1926 bull nose Morris, you do get to meet some strange people in my job!

Got chatting to him, he told me he had a 1924 at home the difference being in 1925 they introduced front brakes as an optional extra! He regards the '24 one as too dangerous to drive on the roads (unless under controlled conditions like a parade or closed rally) but he regularly takes the '26 out for a spin!

found this on the net it was one like this 2 seater but with front brakes.










note no front brake drums!


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## rhaythorne (Jan 12, 2004)

The latest Renault_sport_ Clio, the "197" has a rear diffuser to give an extra 40Kg of downforce at the rear when it's travelling quickly! I can only think of one instance anywhere in the UK where this might possibly be useful:

Bedford Autodrome - South 1/2 after 1KM straight: I've tried going in there at around 130mph and hitting the brakes at the 100M board and ended up totally losing it







Just maybe that extra downforce at the rear would make the difference. On the public roads, the presence of the diffuser is just extra weight to lug around, entirely contrary to its real purpose of course!

Can't wait to hear how ericp gets on at Castle Combe in the Maserati! Not many long straights there to unleash all those horses!


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## Paul (Mar 2, 2003)

rhaythorne said:


> Just a quick thread hijack now that Rog is sorted!
> 
> PG, or anyone, what would you consider to be a "normal" front/rear brake balance on the average road car? Apparently lots of Renault Clio 172 Cups have failed their first MOT's because the rear brakes don't appear to be working, for reasons I wont bore you with. Of course they are working, but it seems that garages who understand the car pass them for MOT purposes whilst those that don't, fail them. The brake balance is something like 90% front / 10% rear. Quite extreme!
> 
> Any comments?


Just hijacking a hijack, my 1972 Renault 12 had a valve twixt rear axle beam and body so that when the car was fully loaded it got more brake force at the rear.


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## johnbaz (Jan 30, 2005)

Just hijacking a hijack, *my 1972 Renault 12 had a valve twixt rear axle beam and body so that when the car was fully loaded it got more brake force at the rear.*


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## JonW (Mar 23, 2005)

rhaythorne said:


> Can't wait to hear how ericp gets on at Castle Combe in the Maserati! Not many long straights there to unleash all those horses!


Er, just dont go too hot up to the bend at the end of the start/finish straight... its bumpy and will cruel your brakes for the next corner and you end up in the tyres...







Coombe is very bumpy and it causes all sorts of problems...



Paul said:


> Just hijacking a hijack, my 1972 Renault 12 had a valve twixt rear axle beam and body so that when the car was fully loaded it got more brake force at the rear.


Golfs and lots of others have the proporp valve on the rear subframe to do the same thing. if you do a lot of 1 up driving the rear disks hardly ever get used and you need to handbrake slow the car a few times each week to clean the rust off the disks or they will need replacment or fail the MOT.

Surely the new MOT computers now have all the details of each car on the system so the Clio data should just need an update?


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## jasonm (Nov 22, 2003)

> and you need to handbrake slow the car a few times


This is normal driving behaviour isnt it







esp for corners?


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## JonW (Mar 23, 2005)

jasonm said:


> > and you need to handbrake slow the car a few times
> 
> 
> This is normal driving behaviour isnt it
> ...


Yes I was only passing on the advice, Ive never had the problem and owned a steady stream of vehicles with rear disks and weight manged prop valves....


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## rhaythorne (Jan 12, 2004)

JonW said:



> Surely the new MOT computers now have all the details of each car on the system so the Clio data should just need an update?


I think the problem is that some testers aren't always sure of exactly which variation of a particular model of car they're testing and the testing rules are becoming increasingly complicated, leading to mistakes.

VOSA issued some advice here (on the last page):

Testing Tips


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