Elantra XD (2001-06) :: 2004 GT Check Engine Light With Code P0420 Listed Twice
Jun 4, 2014
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.
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I just got this very nice Elantra 04 with 64k on it. Yesterday suddenly I got the check engine light on. Today I went to Auto zone and they have checked my car and it showed code P2626. But there are more than a few suggestions about what could be. I don't know what to do. See the attachment below.
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So 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).
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My 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?
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Had the check engine light in the 2005 F150 (90,000 miles) come on. Got the code checked and its P0420. I know that has to do with the cat threshold levels etc. so I believe I am looking to replace the o2 sensor, if I am not mistaken.
How hard of a job is this? Ive done a decent amount of engine work and worked in a shop in high school. Just looking to see if that is the right thing to try first, replacing the sensor, before replacing the cat.
Also I know its the right bank, but if I am not mistaken there is a before and after the cat o2 sensor, which do i replace? Both?
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I 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.
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MK4 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?
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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.
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I own an 04 Hyundai Elantra with around 196,000 miles on it, and have run across a problem I haven't had to deal with before. A few days ago, my check engine light came on while driving. I didn't really notice much, but when I started it again it began idling roughly. I got it home and pulled the code, which was P0341 (camshaft position sensor). This isn't the first sensor I've had go on the car (I replaced an oxygen sensor and throttle position sensor a couple years ago), however I ran into two problems:
1. How likely is it that it's the sensor that's bad as opposed to something like the timing belt or VVT adjustment?
2. Since the sensor isn't horribly expensive, I decided to try replacing it, but I can't get any socket to fit on the bolt that secures it. I've heard it's a 10mm, but nothing seems to fit snugly. Maybe there's just so much crud and corrosion that it's ruined the head. I tried using an extraction socket, but no luck.
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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?
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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.
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I recently had the engine light come up on my Hyundai Elantra 2003. I read the code with my cheap little code reader with the torque lite (free) app on android. It threw the P0128 code which means a faulty thermostat.
Here's the web link to all the details on the code: [URL] ....
I have checked the coolant level and its good. The strength of the coolant is good to -40 Celsius. The engine fan is not running at all. I recently changed the thermostat. I'm leaning towards faulty ECT. The car takes forever to blow hot air too. It has done weird readings in the past with the temperature gauge in the cab.
I just bought a infrared temperature reader of Amazon and want to check the temperature where the water comes out of the engine past the thermostat and compare it to the reading on the torque app readings. I'm thinking it won't match.
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I have a 2003 Elantra GLS. I am intermittently Check Engine light and error code is P0113 - Air Intake sensor issue. I can't locate where the sensor is. I don't see any wire coming of the tubing that connects the air filter to the engine.
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2004 Elantra AT ... 6 months ago top of the radiator cracked caused it to overheat and blow the head gasket and warp the head. Repaired that and compression is fine now. It ran great for 4 months but now it randomly stalls. at or near idle. Seems to do it more at operating temp rather then cold. Occasionally the check engine light will pop on and the code reads (random misfire). It acts just like it has been shut off. But immediately restarts.
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I just bought a used 2004 Elantra that has 97,000 miles on it. When I took the vehicle out for a test drive it was smooth and quite. That was on Monday its now Saturday less than 300 miles later and the check engine light came on and it is having serious hesitation issues?! I am going to take it back where I purchased it from on Monday when they open but in the meantime I would like to know if its could be something simple?
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I have a 2004 standard Elantra GT. I had to get an emissions test and the CEL light will not stay off. My garage replaced two valves in the fuel tank and the neck to the tank and have done numerous "smoke tests" but can't find the leak. Now they are saying there is something wrong with the computer. They got it to stay off long enough to pass the test, but the light's on again. I see that there was a recall issued because of the cracked exhaust manifold, I think I had the catalytic converter replaced up at the cottage.
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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?
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I recently bought elantra 2004 gls, with 107k mileage.
Few days ago the check engine light came on while I was driving it. The next day it went off. This happened today also. I didn't notice anything wrong with the car, no smell, tranny fluid is recent, oil change 2.5k ago.
The code was p0501, speed sensor.
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I keep getting the same code for the check engine light of P0128. I have replaced the thermostat twice and the ECT sensor already. I do know know what else I can do for getting this fixed. I have checked the fans and they are working correctly. I have also checked to make sure there is nothing wrong with the head gasket. My car does not over heat, but it does take forever for the temperature gauge to rise. This is for a 2006 Hyundai Elantra. What else I can do?
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I 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?
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AutoZone provided this code for my check engine light: P0010.
Definition: Intake camshaft position actuator circuit open
Explanation: ECM has detected a low voltage on the VCT circuit
Probable Cause: 1) Open or short circuit condition on the VCT circuit; 2) failed VCT solenoid
Is there a part I can replace myself that can fix this, or is this a dealer repair?
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