Perpexling issue, CEL related.

Jono8

Jono8

Jono8

Caporegime
Joined
20 May 2007
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Surrey
I can not fathom out why this happens and was wondering if anyone else can shed any light on it:

About 6 weeks ago I was travelling back from Ludlow to where i live (near epsom) and as I got on to the M5, northbound at junction 5 my CEL came on after a few hundred yards. I was a bit concerned as i still had another 2 hours of journey left but the car was absolutely fine there was no difference in its operation whatsoever.

I decided to reset the ECU to see if it would come back on again ( in which case i would have gone and got the fault codes read). It didnt, and the car is still running fine so thought nothing of it.

Now, fast forward to this Wendesday just gone, same journey home, same junction/Road, CEL comes on at pretty much EXACTLY the same point . The cars is still running fine and after resetting the ECU again it has not come back on.

Now this strikes me as VERY strange and simply cannot be a coincidence !

Any explanations?

(Car is 2000 Celica)
 
ahh, it's another jumble of letters meaning management light. learn something new every day :)
 
You may well find it's complaining about the catalytic converter efficiency being poor. I've had my car throw a CEL on the same stretches of road before, and it's been that same fault stored every time.

The reason is that once the car has warmed up properly, the ECU will do an emissions check when you're travelling at a cruising speed (so somewhere around 30-50mph depending on what gear you're using). If it finds emission levels are inadequate, it will note the result for that journey but not report any fault. However, if on three consecutive journeys it finds emissions are inadequate, it will flag it as a fault and you'll get the CEL.

Of course, if it then completes three checks later on and finds no emissions issue, then it will clear the CEL itself. Frequent short trips caused mine to get flagged, however after giving the car a good long run it cleared itself again. Get it scanned to see what it is for sure, though.
 
hohum said:
You may well find it's complaining about the catalytic converter efficiency being poor. I've had my car throw a CEL on the same stretches of road before, and it's been that same fault stored every time.

The reason is that once the car has warmed up properly, the ECU will do an emissions check when you're travelling at a cruising speed (so somewhere around 30-50mph depending on what gear you're using). If it finds emission levels are inadequate, it will note the result for that journey but not report any fault. However, if on three consecutive journeys it finds emissions are inadequate, it will flag it as a fault and you'll get the CEL.

Of course, if it then completes three checks later on and finds no emissions issue, then it will clear the CEL itself. Frequent short trips caused mine to get flagged, however after giving the car a good long run it cleared itself again. Get it scanned to see what it is for sure, though.
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Hm, Possibly. I did think it maye be something to do with the Cat conv

My journey to work everyday involves plenty of 50- 60mph stretches however so i would have thought it would throw it up a lot more frequently!

It just seems so weird that it was at exactly the same point on the journey home , 6 weeks apart and we are talking about a 360+ mile round trip. I was properly spooked when it came on! Felt like Déjà vu!
 
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Depends really. Unless you stay between a certain rev range for a suitable evaluation period it won't perform the emissions check, so it's quite possible that you've avoided it on the majority of the stretches of road you use. On two occasions I've had it occur on the same long 40mph road whilst driving to my garage, go figure! :p

Anyway, get it scanned - for all we know at the moment it could be something completely different, and you don't want to unknowingly damage your car whilst using it.
 
hohum said:
Depends really. Unless you stay between a certain rev range for a suitable evaluation period it won't perform the emissions check, so it's quite possible that you've avoided it on the majority of the stretches of road you use. On two occasions I've had it occur on the same long 40mph road whilst driving to my garage, go figure! :p

Anyway, get it scanned - for all we know at the moment it could be something completely different, and you don't want to unknowingly damage your car whilst using it.
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Hm, i dunno. This just doesnt seem to be frequent enough to be paying for it to be checked yet :confused:. Obviously if it was throwing a CEL every week I would be straight up the garage to get it checked out.

I drive it fairly hard a lot of the time so it sees a lot of it's rev range quite frequently. Also, in that 6 week gap I had done a lot of different driving as well, including other motorway journeys.

Thank you for the advice though and you may well be correct. I will definitely take it to get checked if it comes on again.

I just wonder if it could be anything else that would make the entrance to the M5 northbound at Junction 5 throw a CEL at me!
 
radar station nearby? road i used to drive down went near a radar station and it'd cause odd things to happen (reset trip counters etc)
 
why not just get a cheap odb2 reader from ebay for <£30 and have it for life? has saved me a fortune over the years!

Tom.
 
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