Fault code help needed

[LEJ]

Hi, I had the check engine light come on while on the freeway. When I checked via my Durametric it came up with 2 codes: P0420 and P0430 Both say "Short to B+/upper limit/rich mixture Threshold"

Any idea's on how I solve the problem will be greatly appreciated as I haven't a clue as to where to start looking to solve the problem/s.

thanks
Larry

[pomerlo]

Might want to look here to give you a place to start diagnosis.

https://www.discountconverter.com/catalytic_converters_news/news_page.cfm?Key=catalytic_converter-&News=120

[LEJ]

WOW,, Thank you. That was a bunch of good info

thanks again

[Gelbster]

LEJ - seems like you may need a recommendation for a competent ,honest Indie?Local Forum members are a good source of such.Maybe start a new Thread asking that specific question?
Meanwhile the usual suspects are MAF and both O2 sensors.
The Maf is easy to clean.Worth trying
The O2 sensors - monitor their voltage and watch the RKAT/FRA
While you are 'in there' check coils and plugs ?
A good Tech would be able to diagnose the problem very quickly -don't clear the codes !
None of these parts are expensive/difficult to fit but specifying the correct part number is tricky.You need to be very specific with Model/engine size/VIN.
Pomerlo - that was a great link - thank you !
https://www.discountconverter.com/catalytic_converters_news/news_page.cfm?Key=catalytic_converter-&News=120
Let us know what happens?

[LEJ]

Gelbster, thanks for the info. I replaced all 4 O2 sensors and spark plugs less than 2,000 miles ago. I'll give the MAF a good cleaning but the info provided by POMERLO also indicates it could be the Catalytic converter. Further info:: Idle is spot on and no loss of power.
If I need a repair shop, I always go to Precision Motion in Riverside. Great guys and they do excellent work.

[Gelbster]

Originally Posted by LEJ

Gelbster, thanks for the info. I replaced all 4 O2 sensors and spark plugs less than 2,000 miles ago. I'll give the MAF a good cleaning but the info provided by POMERLO also indicates it could be the Catalytic converter. Further info:: Idle is spot on and no loss of power.
If I need a repair shop, I always go to Precision Motion in Riverside. Great guys and they do excellent work.

Pomerlo gave you the best link!
Info by drip feed :-) ?
O.k. -with the new info - different suggestion.
Clean the MAF, do clear the codes and drive a little (to Riverside?) to see if they return .Let PreMo do the O2 Voltage observations, FRA & RKAT. But take the part numbers of all the items you replaced (see my previous post) RND Euro Parts have a reliable site for checking correct part numbers
PreMo will quickly tell you if it is O2 Sensor failure or Cats.
Look carefully at The MAF -does it have a droopy 'nose' ? Look at parts photos to see what I mean. The old part is different.The correct one varies by age/model and to use the new MAF you may need a reflash for the later MAF.There is a TSB but PreMo will do that if necessary.
Tell them if you are using a K&N air filter & have recently oiled it.
Mention any change in Oil Consumption.overfilling of oil, ,Tracking/wild driving/AOS failure.

[LEJ]

The only codes were P0420 and P0430 and according to my the code chart they both read: "Short to B+/upper limit/rich mixture Threshold"

Idle is great, no loss of power, no misfiring that I know of. At 62,000 I had the IMS, clutch, motor mount and coolant bottle replaced, at that time Precision Motion checked the AOS and it had been replaced and was in good condition. I do use a K&N but it's been 2,000 miles since I cleaned and oiled it.
Like I said in the above post, (4) new O2 sensors, 6 new spark plugs at 62,000 miles No oil burning, no excessive oil consumption no overly wild driving (I think?)

[Gelbster]

The oily K&N is a potential problem for the MAF among other things - Search for the negative details.
Obviously there are more serious issues covered previously.

[LEJ]

Update:

As I mentioned in a previous post, I do have a K&N so, I pulled the Mass Air Flow Sensor and used an aerosol can of MAF cleaner and gave it a bath. Not much there to see so no evidence of oil but that doesn't mean anything. Anyway the bottom line is I put about a 100 or more miles on the car trying to replicate when the Check engine light came on. So far, no Check Engine light and hopefully that was the problem.

[Gelbster]

Any K&N oil residue upstream of the MAF potentially provides a reservoir for future MAF-related codes - long after you switch back to a dry filter.

[rexcramer]

+1 for Precision Motion.