I've had both the engine and DSG flash from UM for over a year. The other day I got a cel and a p0420 code. I still have stock dp and oem cats (only Borla cat back). I know the cats are still under warranty (8years 80,000mile). My question is if I bring the car to the dealership for cat warranty will they be able to detect the um flash and use it against me to fix the cat problem?
View 6 RepliesMK4 GTi - My check engine light came on a few days ago and when I checked it, it pulled code P0420.
Just this morning, the check engine light went away.
Is this a common issue? Or should I go get it checked just in case?
I bought my Jetta almost a year ago, and I've been constantly replacing parts. Unfortunately, my engine misfired twice and the CEL has come on for P0420 which is inefficient catalyst. This is the only code being thrown. I've cleared it like 10 times, but it keeps popping up.
View 9 RepliesI have the CBFA motor, and i am getting getting the p0420 error code. I have read two related threads here and here about p0420 codes and different downpipes. It seems the AWE and Nuespeed seem to be better for getting around CEL without additional flashes. I currently have purchased and installed one RAI straight O2 spacer (after the cat) and have tried both the medium and smallest insert but after clearing the CEL it has returned both times with the same code. Do i need two O2 spacers, one installed with the smallest insert and another with a different size? Trying to make sense of all the posts.
I am unitronic stage 1, before going stage two i want to have the CEL under control so i can downgrade the flash and not trip CEL for smog.
Does this mean the DPF is shot? I believe its integral with the cat. whats worth checking first?
View 2 RepliesI keep getting the error code P0420. Cat below threshold.
I have replace both the front and rear O2 sensors and we reset the check engine light. While driving through the cycles to reset the sensors for them to be ready for DEQ, the check engine light came on again.
I am about ready to buy the Cat Converter, but it is really expensive and if there are any other things that I can try before replacing the Cat I would like to try that first. Any other issues associated with that code, or should I just replace the Cat Converter as my next step.
So I recently bought a GTI and started to fix a couple things. It has a P0420 code so I bought a new downpipe to install. Noticed the stock one was missing 1 of the nuts and the stud had broken off. How get this out? Do I need to remove the turbo? Looks like I do need to remove the turbo to use an extractor set.
View 7 RepliesTitle says it. Cat is done. Threw code p0420 and am experiencing hesitation at WOT. Already replaced my front o2 (cbfa) and now I'm debating whether or not to get a new downpipe. I daily the car and am wondering if keeping the car as is for a while will damage anything. Cts turbo has a sale for a catless downpipe.
View 5 RepliesI just bought a 03 2.0 and ive been trying to fix her back up, she is almost there, just waiting on my first gear getter from diesel geeks and trying to figure out why these codes (p0420 and p0141) keep coming back on. Originally it was just a p0420 code so i took out the upstream sensor and cleaned it, then i took out the backstream and after examining it figured it should be replaced.
I went and bought a new one and replaced it, within the next 2 days the check engine light came back on throwing the original p0420 code along with p0141 this time. So i took out the new down stream 02 sensor and took it back to autozone and they swapped it out with a new one for me free of charge. So i put the newest 02 sensor in and then within 2 days, both codes p0420 & p0141 came back on. Two 02 sensor heating wires being bad i feel is a pretty slim chance. What is possibly the cause for these two codes repeatedly being thrown?
2001 Jetta 2.0, manual trans
I've been having problems with intermittent P0420 cat below efficiency code. Everything else is fine, no codes, runs great. I tried spacing the post cat sensor back w/ extender bung (after replacing post cat sensor..) and still get the code. I don't hear any rattling or anything to make me think cat is bad physically. I was told by dealer that a code update might resolve for $200 - which got me thinking that that if that was so, it should should be a problem which Feds should be aware.
I searched safercar.gov and found this NHTSA ID Number: 10054864
It's a service bulletin saying that VW made the limits too sensitive and it seems there was a customer satisfaction campaign to update code - pdf on site CSC-10054864-8736
It says:
May 2007
Subject: Emissions Service Action N7
1999-2002 Jetta, Golf and GTI with VR6 Engine
Update Electronic Control Module (ECM) Software for Catalytic Converter Monitoring System Dear Volkswagen Owner: We are writing to inform you of an emissions service action on some 1999-2002 Jetta, Golf and GTI VR6 engine vehicles. Our records show that you are the owner of one of these vehicles.
What Is The Problem? The electronic control module (ECM) software for the catalytic converter monitoring system is too sensitive. This can cause the MIL to come on, and some vehicles may exceed Federal and/or California emissions standards. Also, in some cases this leads to unnecessary catalytic converter replacement. What Will Volkswagen Do? Dealers will update the ECM software.
2003 Camry 2.4L 4cyl
I noticed my engine light turned on. I went to Autozone to hook the car up to the computer. The computer printed out the code P0420. My coolant temp is normal. What can this code mean. The car has over 126,000 miles.
I have recently had about $1620 worth of work done on my 2000 4Runner because the check engine light came on and the code was P0420.. My invoice says they replaced the exhaust pipe assembly. Now 2 weeks later the light is back on with the same code...are the 02 sensors part of the "exhaust pipe assembly" or are they now going to tell me I need a bunch (2-4) 02 sensors replaced.
View 3 RepliesOn my 2002 (AVH) 2.0L 4cyl Jetta I have a persistent P0420 error code: "Catalyst System Efficiency Below Threshold"
I changed the oil, cleaned the Mass Airflow Sensor, replaced the coolant, thermostat, and coolant temperature sensor. But it's still showing up.
OBDII says it could still be:
A damaged or failed oxygen sensor (HO2S)
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire Oil contamination
I bought an 04 elantra a few weeks ago. The check engine light is now on and I get code P0420 listed twice with my code reader. I have replaced the downstream O2 sensor and reset the codes only for them to return again. It is my understanding that this is going to be a convertor problem. My question is that from the research I have done it looks as though this car has two converters. One at the exhaust manifold and then another in the tailpipe. Which one is going to be the most likely causing my Check engine light to come on. Or do I need to replace both converters.
View 5 RepliesI have a 2003 Toyota Corolla, mileage app. 106,000. Check engine light first came on when driving to destination 40+ miles away (most of my driving is shorter, around-town trips). My mechanic said code is P0420 and so they reset it and said if it comes on again that I need a new cat converter. It did not come on until about 6 weeks later when I was on a longer trip again (had driven about 40-50 miles). Can you tell me if the P0420 code absolutely means that a new cat. conv. is needed or if it could possibly be a sensor or something else hopefully less costly than a new cc?
View 3 RepliesI have a 2001 Honda Odyssey with 90000 miles. Lat last year around Oct/Nov time frame, check engine light came on. I took my vehicle to a local Auto Zone store and they scanned the code and told me it was P0420 - bad catalytic converter.
I replaced the cat converter with an after market model, however after 3/4 months (after driving 2000 to 3000 miles), check engine light came on with the same code. The mechanic changed the cat converter and put a new (after market model). Again after 3/4 months (2000 to 3000 miles) check engine light came on again. And this time the mechanic replaced the cat converter and also oxygen sensor. Now after 4 months or so the check engine light is on the vehicle again.
The mechanic is now saying that the problem is not with the cat converter and he is saying there is a lot of abnormal deposit on the vehicle. When he scanned again he found another issue that read something like "high voltage" and this time the guy thought may be due to short circuit (per code) the fuel injector is sending high volume of fuel and this is causing excessive fuel to go into the cylinder and hence high volume of emission. I replaced the fuse box again and after another 100 miles or, the problem is reappearing.
My 2005 Dodge Dokota 4.7L V8 152,000 miles has an intermittent check engine light (CEL) code P0420 ('catalylst efficiency') that turns itself off.
1) 151,000 CEL on, code P0420, checked, cleared at dealer.
2) 151,948 CEL on, code P0420, checked, cleared at dealer (Cat Conv).
3) 152,200 CEL on, code P0420, checked, cleared at local auto parts store.
4) 152,597 CEL on. No checks.
5) 152,815 CEL turned off on its own
6) 152,849 CEL on. No checks.
7) 153,137 CEL turned off on its own.
Twice in this time CEL has came on soon after a fill up from near empty.
Engine runs fine, 18-19 mpg highway.
Have seen numerous on-line reports of other possible causes:
a) base engine problems (coolant or oil) -- coolant temp sensor
b) Air inleakage -- air systems or manifold
c) Lazy front O2 sensor
d) fuel pumps
e) timing or misfire
f) what else? - (gas cap, other...)
What to check first or categories to eliminate?
I was driving along today and my Check Engine light came on. I stopped at the nearest Advance Auto to have them pull the code and it came up with the P0420, Catalyst Efficiency Below Threshold (Bank 1). I asked what could cause this and they mentioned that the fuel that was put in could be causing it. They didn't mention any other possible causes. Any others? I'm thinking it could be the fuel because the last gas station that I stopped at and filled up at is one that I never go to, and maybe just got a bad batch of fuel.
View 14 RepliesSo today my CEL came on. I immediately looked at my mileage and I was EXACTLY at 500m past my oil change the other day. I checked the dip stick and lo and behold, it was about 3/4" past the full marker. I took it back to the oil change place and had them drain it down to a good level.
I had driven from NH to NY this week. I filled up my gas tank on my way home from NY. Gas cap was on nice and tight for sure.
The code is still on (not sure how many miles or drive cycles is required) for something to clear. I figured it was perhaps due to too much oil added. I decided a few hours later to take it to AutoZone and grab the diagnostic code. It's a P0420 code (Cat System efficiency below threshold: Air leak in exhaust before rear HO2S, AF Sensor Error, Fuel System Fault, Faulty Catalytic Converter).
Book says "catalyst system efficiency below threshold (Bank 1)".. Is it just based on mileage or an actual bad O2 sensor or other bad system component?
View 14 RepliesMy check engine light has been coming on and off and it seems to show P0420 for catalytic converter. The light stays off for about a week and it'll come on for a day or two and off again.
Wouldn't a failed converter stay failed? Can P0420 be triggered by loose/bad gas caps?