Trouble shooting codes P0507 and P0420 on 2003 Nissan Altima

Kit L · **Joined:** Thu Sep 25, 2008 9:51 am **Posts:** 1

Is my catalytic converter defective, or a vacuum leak.?
I went to auto zone and they hooked my car up to their
machine to figure out why my check engine light is on. This is what I found out.

TROUBLESHOOTING CODE: P0420
The oxygen sensors monitor the catalytic converters ability to store oxygen.

My catalytic converter is defective because I might have these problems:

1.Engine misfire or running condition.
2.Large vacuum leak
3.Engine oil leakage into exhaust valve guide seals, piston rings.

ALSO came up with:
TROUBLESHOOTING CODE P0507
IAC Circuit condition or Idle speed higher/lower than expected

The ECM has detected that the IAC counts are highter/lower than expected, the engine speed is not in its expected range.

1.Vacuum leak on engine
2.Dirty throttle body
3.IAC motor defective
4.Poor electrical connection to the IAC valve

I have recently replaced Camshaft, Crankshaft sensors, Coil-pack on #3 was misfiring and alternator.
Now when it is idle the idle is like surging up and down

Can anyone give me a explanation of what that means or how to fix it? I have a 2003 Nissan Altima 2.5.

Sponsored Links · **Joined:** 29 Jun 2004 08:12 pm **Posts:** N/A

jeff compton · **Posted:** Thu Sep 25, 2008 1:25 pm

probably vaccum leak form the intake gaskets, very common, lots of posts about it, start there!

asecmt · **Posted:** Thu Sep 25, 2008 3:39 pm

P0420 IS MOST LIKELY THE CONVERTOR..THE P0507 IS USUALLY DUE FROM THE A DIRTY THROTTLE BODY OR ONE THAT HAS BEEN CLEANED AND THE IDLE RELEARN HAS NOT BEEN PERFORMED. DID YOU MESS WITH IT WHEN YOU REPLACED THOSE PARTS? ANY WAY IF IT IS DIRTY AND THEN CLEANED YOU HAVE TO DO A IDLE RELEARN WITH A OE LEVEL SCAN TOOL. THESE THROTTLE BODIES GO BAD ALL THE TIME TOO.

curlyelp · **Joined:** Sun Mar 22, 2009 10:10 am **Posts:** 5

asecmt wrote:

P0420 IS MOST LIKELY THE CONVERTOR..THE P0507 IS USUALLY DUE FROM THE A DIRTY THROTTLE BODY OR ONE THAT HAS BEEN CLEANED AND THE IDLE RELEARN HAS NOT BEEN PERFORMED. DID YOU MESS WITH IT WHEN YOU REPLACED THOSE PARTS? ANY WAY IF IT IS DIRTY AND THEN CLEANED YOU HAVE TO DO A IDLE RELEARN WITH A OE LEVEL SCAN TOOL. THESE THROTTLE BODIES GO BAD ALL THE TIME TOO.

Well I have replaced the cat 3 times now and the P0420 code keeps returning, so it is obvious the problem is some where else...

asecmt · **Posted:** Sun Mar 22, 2009 2:42 pm

that all depends on where the converter come from...

curlyelp · **Joined:** Sun Mar 22, 2009 10:10 am **Posts:** 5

asecmt wrote:

that all depends on where the converter come from...

I bought the first @ $80, "Universal", the second was also a Universal but more expensive, $120, and finally the last one was a "Direct Fit" $225. And the code takes about a month to return, then about a Day from there. I still think that the converter "AGAIN" ... Is Too Much!!!

asecmt · **Posted:** Mon Mar 23, 2009 4:33 pm

I cant stress enough OE or OE quality will only work...

drjughead03 · **Joined:** Mon May 11, 2009 2:13 pm **Posts:** 1

Hi...

I have the same code P0420 popping up for my 2003 altima 2.5L

My cat converter is gone..I am confused Is there a separate cat for top and bottom ?

I read here that universal cat cost 80$..can u suggest some good link to buy...My dealer gave me a estimate of 1000$..

Plz advice where to buy Cat and are there 2 cats for top and bottom or just one...

Thnx

Trouble shooting codes P0507 and P0420 on 2003 Nissan Altima

Who is online