L1th1um67

Hello everyone,
02 chev venture LS - 159k miles

I had some exhaust work done earlier today and about 6 hours later my service engine light came on. I stopped at autozone and had them scan it and p0420 came up. I know that it's the catalyst efficiency below threshold bank 1 code and I did research it and found it could be anything from spark plugs and wires to the cat itself. I read all about all of that fun stuff....
My question for you folks is- is there some kind of correlation between having my exhaust fixed and this code coming up? Is there something that fixing the exhaust leak (and muffler) would cause this code to come up? I am not a mechanic but I do know basic car stuff (how to change a tire/oil & tune ups and other routine fixes) so I don't have the benefit of lots of car experience. If you can think of anything let me know. Thanks!

chevy47390

Hello
DTC that which originates the O2sensor, in principle reflects an abnormal presence of oxygen in the exhaust gas. Just like stoichiometric wrong.

it depends on what part you worked, but if you have worked on, just a gasket is not properly seated, or a leak, so that air is sucked (deceleration for example) and detected by the O2 sensor. this will cause a DTC.

if you worked on eshaust pipe after the O2sensor probes, check their connections

huntersdl

I am new here .. I registered to help research for my father in laws 99 venture with 175k miles and starting to have lots of problems. I am very familiar with this code though and yes it is the cat code. If you had work done it could be an air leak, a plug, they forgot to hook the o2 sensor back up or put it in.. could be several things. One thing though IF and WHEN your cat goes bad (assuming the mesh etc is whole and no holes) you can take the cat off and soak in a big bin overnight... with citric acid and laundry soap.. agitate every few hours..... rinse blow with leaf blower to get as much water out and off as you can and install with new gaskets. Your CAT will work great again - you know cats are a little over a few dollars

L1th1um67

Thanks for answering folks. Sorry I didn't get back to you... this Venture has turned into a nightmare for me and I swear I've been under the hood everyday since I bought it in December. The cat code was the least of my problems... I was able to get it tailpipe tested and it passed emissions here in Ohio. I just took the negative off the battery for a few minutes to reset the computer... it wasn't ready for OBDII testing so they did the old style tailpipe sniffer test thankfully. I know they don't do that in many states, in fact if computer isn't ready they will just fail you! But luckily here in Ohio they don't auto-fail u for that.

I don't think there is anything wrong with the cat... it doesn't seem clogged. I can jump on the gas and it will not bog down or anything (my old venture had a clogged cat so I know what to expect). If I can ever get a chance to go underneath the thing I will look for something improperly installed...per your suggestions.

I'm going to look through the threads here and see if I see anything related to my newest issues... Jesus. It's awful. I've driven it a total of 400 miles since December 5th of last year. It's now March 15th. It's become a nightmare for me!

chevy47390

The fault has occurred with the change or work on the exhaust.
But if everything is in order or appears to be, you have to push the analysis of alarms . Unfortunately, the default may occur simultaneously or nearly so. We focus on the first fault or what we did , but the fault lies elsewhere. ( I recently changed the connection from the battery to the European system, that's afterI had problems starting , I thought of my connections , but it was the starter holder bruhes that were completely worn out !)

You absolutely need the device that plugs into the OBDII , which reads error codes and gives you the operating parameters of the engine.

this type of device gives for example :

Fuel sys 1 : CL closed loop or open loop OL
Load Pct %
Eic ° C
SHRT FT1 shorttime injection
Long FT Longtime FT1
MAP 35-38 KPa idle
RPM / min
Vss 0 ? ?
Spark ADV about 20 °
IAT
MAF g / s about 4 idle
TP 0.0 % ?

and especially :

O2 B1S1 Lambda sensor input cat between 0.200 and 0.800 mV

O2 B1 S2 cat Lambda sensor output between 0200 and 0800 mv

this unit that can be purchased for a hundred dollars, allows direct reading of lambda probes, these two parameters
This unit is essential to act intelligently on his car and on all vehicles since about 1996 . and thus our Ventures

If there is a lambda alarm this can determine what is the analysis probes too rich or too lean. Actually too poor example is the presence of oxygen in abnormal proportions , so too much oxygen which results in poor combustion , incomplete whose causes can be quite varied and different : bad ignition coils failing , but it can also be insufficient lack of fuel injection .
or intake air into the exhaust system before the probe course .

The whole point of the device is that it can guide the diagnosis in the right direction.

when the coils begin to be faulty O2 B1 S1 is always beyond 1100 .

There are several years I bought this device, but there are only a few months I understood these operating codes .



I do not think it is wise to reset the PCM and is a very successful material that reacts to input parameters . this is a maneuver when everything actually failed. If there is a DTC , there is an entry that is not in conformity .
sincerely