Engine Light - MAF, Oxygen Sensor or Cat?

[Skitzyrex]

Good Morning,

So I'm having problems with my 2007 TB48 GU. The engine light is on and after taking it to Nissan they tell me it could be any of the above problems. Now I get that it could be the MAF (I've now replaced and its still on) or any of the four oxygen sensors (I've replaced the two upper ones so far), but how could it possibly be the cat which is half way down the exhaust? There are no sensors past that point so how could it be throwing a code?
The fuel economy, if you could call it that, has just gone from bad to absolutely shocking so if there is some Guru that can maybe clarify my Cat question I would be very grateful.
Thanks Mick

[taslucas]

Gday Mick, im thinking the only way it could be the CAT is if its blocked up and perhaps pressurising the exhaust up to the oxygen sensor?? That would also make fuel economy worse.

Completely guessing though mate, hopefully someone with some more knowledge comes along soon

[my third 256]

try cleaning the maf sensor this can cause shithouse fuel economy have a look at this link
http://www.nissanpatrol.com.au/forums/showthread.php?597-Checking-and-cleaning-MAF-sensors

[Skitzyrex]

Gday Mick, im thinking the only way it could be the CAT is if its blocked up and perhaps pressurising the exhaust up to the oxygen sensor??

Can now confirm that's no longer a problem if it was before. Should the light just go off if it was the problem? Or does Nissan have to reset it again?

[Skitzyrex]

try cleaning the maf sensor this can cause shithouse fuel economy have a look at this link
http://www.nissanpatrol.com.au/forums/showthread.php?597-Checking-and-cleaning-MAF-sensors

Cheers mate, I've replaced the maf with a brand new genuine unit the other day after previously cleaning it with no luck.

[my third 256]

disconect battery for a few hours then should be ok

[Skitzyrex]

My scanner came today and it through code p0113 which is the air intake sensor. Now by all accounts on my model this is in the maf sensor which for me is brand new.
I have reset the code and it came back within a few seconds.
Any other ideas?

[Bulbous]

Don't Australian TB48s have more than one cat? that's why the 4 O2 sensors.
I saw a picture that showed 2 very small cats in the downpipes from the manifold, 2 O2 sensors before and 2 after. If I can find the picture I will post, with a copy of my setup (Gulf Spec = 2 O2 sensors).

I recently replaced my complete exhaust with headers and a drainpipe ( sounds like) - I occasionally get the engine light to come on when the engine's cold. It goes out after 5 - 10 mins.
Cold here is a relative term :) It seems hot to me, but obviously the engine is cold enough to engage the cold start system and enrich the fuel supply.

[Skitzyrex]

Don't Australian TB48s have more than one cat? that's why the 4 O2 sensors.
I saw a picture that showed 2 very small cats in the downpipes from the manifold, 2 O2 sensors before and 2 after. If I can find the picture I will post, with a copy of my setup (Gulf Spec = 2 O2 sensors).

Yes mate, I now know it has 3 cats. The oxy sensor code though is no longer coming up after replacing the sensors.

[Higgo]

Hi, just wondering if you found the fix for your TB48 fault from years back? I've got a similar fault on mine and was wondering what the eventual fix was on yours. Cheers.