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CAT + Injector light + consumption!

1K views 13 replies 5 participants last post by  McGuinn 
#1 ·
Can anyone shed some light on my little problem? Sorry to ask so much in one thread!

The injector warning light is lit on my 1.6ts 146. I know that my CAT has completely gone :-( but could this be why the light is on? Anyone ever had this light lit on their dash?

Also, would the CAT being completely shot to pieces affect fuel consumption? I do quite a lot of motorway miles (which I thought should be economical!?) but only seem to get around 270 miles from £30 of petrol. Does this sound normal?
 
#2 ·
Hi Stevo, yes, that's the reason why that light is on (it has to do with engine management) and also why the fuel consumption might go up (not because of the light but the problem with the cat ;)).
 
G
#4 ·
How do you know the cat has definately gone? A failed cat wouldn't give an error reading afaik as everything that's tested is before the cat.

Sounds like your lambda might be shot or something else giving the error message. Perhaps an intake leak, water temp sensor etc etc.

wrinx
 
#5 ·
What I think he's telling us is that the cat is all rusted and ready to fall off. :D At least that was the idea I got...
The light on is not a signal from the cat (of course) but from one of the lambda sensors somewhere in the exhaust line.
 
#6 ·
THROTTLEMAN said:
What I think he's telling us is that the cat is all rusted and ready to fall off. :D At least that was the idea I got...
The light on is not a signal from the cat (of course) but from one of the lambda sensors somewhere in the exhaust line.
Yeah that sounds about right. The CAT is gone and failed the emissions test on MOT. Garage said that a "phase sensor" in the exhaust was the probale cause of the injection light being on, but thought maybe the CAT being damaged might have been another reason.

Are lambda sensor problems quite common? Has anyone else has this, and is it expensive to fix? What would happen if I didn't get it fixed?
 
G
#7 ·
The "phase sensor" in the exhaust they are on about will be the lambda sensor but never heard it called that before :rolleyes:

Be careful of garages telling you the cat is dead, they are often wrong and it's the lambda or water temp sensor over fuelling the car.

Lambda problems are VERYcommon. They are designed to last about 60k but some do much more (and less!). About £80 to replace.

wrinx
 
#8 ·
Dodgy Lambda's on 146s are very common. The lambda is attached to the Cat and measures the heat/amount of oxygen in the exhaust gases.
If it has gone you will get...
Excessive fuel consumption
The FI warning light will , er, Light up
You may get "hunting at low speed", a tendancy to feel like the car is about to stall.

I would definately replace the lambda ( £40 + 30mins fitting) before I replaced the cat ( £6-700 )

I have personal experiewnce of this and have advised 4 people with the same symptoms you describe, no-one has replced a cat yet :D

:) JaB
 
#9 ·
JaB said:
Dodgy Lambda's on 146s are very common. The lambda is attached to the Cat and measures the heat/amount of oxygen in the exhaust gases.
JaB
Not true on the older range of cars.
The CAT sits down-stream from the lambda, with the lambda inserted in the exhaust downpipe after the branch section. The reason for having a lambda is to measure and control the emissions and prevent unburned fuel from reaching the CAT, causing damage.
On newer cars, there are multiple lambda probes; on the 146 there is only one.

Anyhow, a disconnected lambda sensor should cause the error light to display, but a malfunctioning one won't. As Wrinx said, the ECU is complaining about the phase sensor, and this is probably the lambda... but bear in mind that a true 'phase sensor' is a device that measures the angle of a rotating wheel... so that could the the cam-shaft phase sensor or even the TDC detection on the flywheel...

Sorry If this confuses you Stevo, but better knowing something about how the engine works before having your wallet lightened... :)
 
#10 ·
Thanks for all your advice everyone. My g/f's dad is doing the work for me. He's got a cat for about £160 (i think) and is going to fit it for me. Sounds like I should get the Lambda done at the same time in case that is what the problem is.

From what i've read above, a broken lambda will cause my new cat to be damaged anway, so surely fitting both would be a good idea, if I've already bought a new cat. :mad: :lol:
 
#11 ·
Yes, it will damage it over time. The unburned fuel will react with the reactive metals and degrade them. But again... it may still be a problem with the lambda and not the CAT.
 
#12 ·
i have a similar problem with my 156 1.8ts the light comes on about 10 mins after first starting and the main cooling fan cuts in and stays on with the light. it has just failed mot on emissions so i gotta dig deep and take it for a reading at a decent diagnopstic sensor.
could the lamba sensor cause the fan to run and the emmissions to be high?
 
G
#13 ·
Wonder if that could be something like the water temp sensor or rad switch (if fitted). The water temp sensor does input in to the control of fuelling as well but no idea if it has anything to do with the fan.

wrinx
 
#14 ·
I'd advise have a look at the sensor specifications in the service manuals.
Each sensor can be tested with a basic multimeter to a fair degree to determine whether it's functional or not.
You're only reading the resistance of the device in most cases, and it can be done while the engine is off.
 
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