Honda - Accord - Code :: P0420 - Catalyst System Below Efficiency / Bank 1
P0420 Catalyst System below efficiency -- bank 1
I've had this code for a couple months trying to trouble shoot it. My gas mileage has been affected, as I'm getting about 23/24 MPG city/highway. I replaced the upstream 02 sensor with am aftermarket Bosch variety( I'm not sure why a non-OEM one would make a difference, as long it's working correctly).
My car has 253k miles, the cat doesn't rattle and I don't smell any rotten eggs or anything, but it has to be clogged or the 02 sensor I got was defective. My engine runs fine and I don't have any problems accelerating or decelerating. It may still be the 02 sensor since the gas mileage decrease is so significant, or it could be my converter is really clogged up.
Golf IV / Jetta IV :: Error Code P0420 - Catalyst System Efficiency Below Threshold
On 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
Subaru - Outback :: Intermittent Check Engine / Code PO420 - Catalyst System Efficiency
My 2004 Outback now has 120K, has always been maintained and repaired at the dealership (except tires and battery), and has always run great! I've had the plastick-y parts replaced over the last few years including head gaskets when one cracked and made smoke. In July I got a jump from a AAA tow truck, who said my battery tested as needing replacement.
In September my check engine light went on, and the dealer found the code PO420-catalyst system efficiency. They didn't seem to look any further into causes. The cat converter replacement was to cost $2521. They reportedly tested the battery as OK as part of their routine checkup. I declined the new cat converter till learning more. Meanwhile, my check engine light seemed to cycle on, then off, then on, then off . . . every several days.
In December I had the battery checked at Sears, who replaced it under warranty. So I guess it wasn't okay after all. After that my check engine light stayed off for somewhat longer than usual, then back on for most of January. I was just about to give in and get the repair done when it cycled off briefly a few days ago.
I've lost trust in the dealership because of their battery check which differed from others before and after theirs; and for their lack of specific diagnostics. The light is back on and I don't know what to do next.
Toyota - Camry :: Check Engine Light Code - Catalyst System Efficiency Below Threshold
My 1999 Camry with 169700 miles has this 'check engine light' code: "Catalyst system efficiency below threshold". We have a mechanic we trust so we'll bring it to him this week. We spent a couple thousand fixing this car about two years ago and I'm not sure it is worth doing that again. Carmax offered us 1200 for it around this time 2012.
View 17 RepliesFord - Explorer :: Check Engine Code P0420 - Catalyst System Efficiency Below Threshold
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 RepliesPrius (2004-09) :: Check Engine Light And Code 0420?
I had a check engine light and code 0420, which after researching I decided to replace the cat with an aftermarket - Magnaflow 99205HM. Spent some time driving around today and the light is back on!
View 1 RepliesPrius (Gen 2) :: Engine Misfiring - Catalyst System Efficiency Below Threshold Bank 1
I've got a 2004 Prius with about 140,000 miles. Overall, the car has worked great, and I've kept up with regular service.
Several months ago, I started having bad misfiring of the engine. When I got it into the shop, it turned out to be two faulty ignition coils. The shop advised me to replace them all, which I did. Soon afterwards, however, the CEL came on, indicating a P0420 - "Catalyst System Efficiency Below Threshold Bank 1".
Lexus RX 2004-09 :: RX330 - P0430 Catalyst System Efficiency Below Threshold (Bank 2)
CEL and VSC came on so i ran the diagnostic tool and got this msg :
P0430 Catalyst System Efficiency Below Threshold (Bank #2)
what could it be? The car performs fine, no MPG decrease, no performance impact..
Lexus GS 2006-11 :: GS450h - P0430 Catalyst System Efficiency Below Threshold Bank 2
Have the EML on on my GS450h, read the fault codes and I have 2 fault codes that are identical (P0430). I cleared the fault codes and it stays off for a day, then as soon as I go above 60mph the next day, it comes back on again, the faults are stored and not current codes. I've not noticed any MPG loss or loss of power whatsoever! So am I safe to assume its not the catalysts? Only other thing I could think of is an o2 sensor gone bad perhaps? I don't want to spend money really as I'm about to sell the car for a more economical one for my 150miles per day commute to work! Just had all 4 wheels refurbished too which set me back a fair amount, now this!
View 2 RepliesSanta FE SM (2001-06) :: Code P0430 - Bank 2 Cat Efficiency Low
05 santa fe/3.5L/ owned since new. Had a misfire problem and solved that by changing coils/plugs/wires...
Still getting a P0430 code (bank 2 cat efficiency low)
Following the Repair manual troubleshooting of that code says
Read H02S - got a scan tool and did that -
Comparing Bank 1 H02S1 and 2 show they are are different voltages and do not follow.
Comparing Bank 2 H02S1 and 2 show nearly identical traces.
I also checked the wiring harness around the sensors and check for air leaks...couldn't hear/see/feel any.
My conclusion based on the info obtained is that the bank 2 cat is bad and needs to be replaced.
Golf IV / Jetta IV :: P0422 Code - Main Catalyst Below Efficiency
I have been trowing a P0422 code which is main catalyst below efficiency.
I recently changed the rear o2 sensor and about 60 miles later the same code came back.
Logic dictates that the Cat is bad or there is an air fuel issue. No other codes have been thrown.
The car is a 1999 Jetta 2.0L AEG engine but it only has 51k miles on it. Would the cat go bad in 51k miles?
What else could I be looking at?
Elantra XD (2001-06) :: P0420 Code - Catalyst Efficiency Below Normal
P0420 code. Catalyst Efficiency Below Normal (Bank 1)
This was the explanation I got from autozone. First question is how serious is this? The car seems to drive fine and normal, but I just purchased this car about a month ago. The light turned off after the guy at autozone plugged in the scanner. I am sure it will come back on again after some driving. Is it ok to drive with it on?
Touareg :: P0420 Bank 1 Efficiency Below Threshold Code Keeps Coming Up?
Recently I pulled code P0420, AKA Bank 1: Efficiency Below Threshold.
To start from the beginning...several weeks ago my EPC light came on so, like most educated consumers I decided to buy a vag-com. I pulled the codes and got both the Bank 1 and Bank 2 efficiency below threshold codes (p0420, p0430). I reset the light and literally within 3 minutes the EPC light came back on only this time just Bank 1.
So I drove around again for a week and the check engine light came on this time, back to Bank 1 and Bank 2. Whether trying to replace the spark plugs will possibly fix the misfires, its Cat Converter replacement or possibly just replacement of 02 sensors. I have been reading mixed responses.
FYI I use synthetic oil and chance the oil every 7500-9000 miles, have 89,000 miles and have never changed my spark plugs.
Maintenance / Repairs :: Code PO430 / Catalyst Efficiency Below Threshold
I was app. 10 miles from home & engine started missing & went into limp mode & yes the light flashed . I limped it home anyway & now have a PO430 code . # 2 spark plug died & caused this , danged plug didn't have a hundred miles on it since new . Replaced that plug & everything's fine except that code . Vehicle runs great . I've also read an 02 sensor could cause this code .
View 4 RepliesGolf IV / Jetta IV :: CEL On - Exhaust Leak Throwing Catalyst Efficiency Code
I'm working on a 2003 Jetta GLI 1.8t (MT and 140,000m if it matters). The CEL has been on for a couple of weeks because of an exhaust leak throwing a catalyst efficiency code. After I make this post I'm going to run down to the advance auto I used to work at & see if I can borrow the scanner to see if there's anything new, but as of right now I don't know. I'll update the thread if I find anything.
The car started yesterday AM perfectly fine. Started again when I left work around noon. No problems with the start, idle, acceleration.. it's all good.
3 hours later I tried to start it to go pick up my kid from school but it just cranked without firing and would not start. I took care of business with the kiddo and then started trying to pin down the problem.
1. Opened the door & listened for the fuel pump to prime.. No sound.
2. Noticed the dome light is on.
3. Checked ALL of the fuses on the side of the dash.. All are fine. Turned key to listen for secondary prime.. no sound.
4. Bought Fuel pump relay & replaced.. no change.
5. Cursed.. a lot
6. Bought fuel pump.. replaced.. no change.
7. Cursed a lot more.. and cried a little too.
8. Noticed the fuel pump was now priming with the key being turned, but still not when I open the door.. Dash indicates the known CEL, but now I notice that the EPC light is on too (this could be from all the fruitless cranking drawing down the battery charge)
9. Figured I'd throw in a new crank angle sensor cuz of the EPC.. no change.
10. Shot starting fluid down the intake.. didn't hit a lick.
I feel like I'm at a dead end.. It's acting like a bad ignition control module, but there's no such thing on a vw 1.8t.
Golf IV / Jetta IV :: 2001 - Intermittent P0420 Cat Below Efficiency Code Appears
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.
Prius (2004-09) :: CEL On / Code P0420 / Catalytic Converter Threshold Below Efficiency
I checked out a 2006 Prius yesterday a guy is selling. It had the CEL on (not sure why somebody would try and sell a car with that, but anyway). He said that it's because they get gas at a station that consistently doesn't tighten the gas cap enough but by the time the tank is down to 1-2 bars the light always goes away. Although I don't doubt his story, I absolutely doubted the cause. So I took it to get the code pulled and it was P0420, which is catalytic converter threshold below efficiency.
View 15 RepliesDodge - Dakota :: Intermittent CEL / Code P0420 (Catalyst Efficiency) That Turns Itself Off
My 2005 Dodge Dokota 4.7L V8 152,000 miles has an intermitent 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 in leakage -- 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?
Ford Escape / Hybrid :: 2002 V6 - CEL Code P0420 For Low Cat Efficiency Bank 1
I have been getting a CEL P0420 for low cat efficiency bank 1 on my 2002 Ford Escape V6. The truck runs fine otherwise. I have ran two loads of Cataclean and the light keeps coming back a few days after CEL reset so I am pretty sure one of cats is done. I am going to replace with an aftermarket cat. My question is, with this code, do I need to replace the front exhaust manifold cat or the rear manifold cat?
View 1 Replies