Ford F-150 (2004-2008) :: 2005 - Check Engine Light Code P0420 - CAT Threshold Level
Mar 18, 2011
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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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?
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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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2004 F150 5.4L V8 ...
P0420 Catalyst below threshold bank ...
O2 Sensors or Catalytic Converter ...
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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 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.
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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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99 Ford Ranger 4-cyl. Check engine light is on; pulled fault code: "catalyst efficiency below threshold, bank 1." Cat converter is new as is rest of exhaust, o2 sensors are new, and its been recently tuned up.
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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.
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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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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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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.
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I took my car to get inspected today and it was rejected because of P0420 and P0430: Both Catalyst system efficiency below... My check engine is also on.
I have the full Meisterschaft exhaust installed (+midpipe) PPE headers and K&N intake. Whats the problem and how can I get this fixed so I can pass the inspection?
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I have a 2006 Subaru Forester with 95,000 miles on it. Earlier today the CEL (solid) and cruise (flashing) came on while I was driving. I believe it may have occurred as I was accelerating up hill. I filled up yesterday, so I tightened the gas cap when I stopped. On my way home, I stopped by my mechanic and they read the code; P0420 Catalyst Efficiency Below Threshold Bank was the code that was read. They reset the code for me but told me that the catalytic converter is what needs to be replaced.
My question: Could the light coming on be incidental (i.e., is it possible that it was a "blip" and my catalytic converter is okay?)? My mechanic said he thinks it is, and that my car should last me quite a bit longer. I am asking because I've put in a bit of money into the car of late and I'm wondering if I should just jump ship. I should say that the majority of the repairs are maintenance (e.g., brakes, tires).
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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
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I have engine light on and the code is PO446. just changed fuel filter on my 2006 5.4L f150. What the code means ?
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So the check engine light came up on my truck and I scanned it to find P0021 which is Intake camshaft over advance or VCT solenoid stuck open. I really doubt my truck skipped timing and all the research I've found had it linked with other codes requiring cam phasers. The truck is a 2008 F150XL with the 5.4 Triton with 90k on it
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I have a 2005 f-150 with the 5.4 engine. Bought it new and now it has 107,000 miles on it. Recently,it would have a shudder at 65 or 75 mph then the passing gear would kick on and it worked perfectly. The warning check engine light came on,then,when it acted up it would flash intermittently. Took it in to the dealership and put it on the diagnosis machine. Said cylinders 2,3, and seven were not steady etc?? So,after he took it out and drove it he said those particular cylinder walls were scored. I put in a K-N air filter at about 50,000 miles,and he said that they do not seal properly and dust got by the filter into the intake and got into the engine and did this damage. One think he found was a bad coil on one cylinder and replaced it. And just as he said,when I got on the road home I romped on it and it cut out and the intermittent signal showed again! He said that that would happen and it did.
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I have a 2005 f150 with 96,000 miles. Long story short, last August I was headed to the mountains going up a steep long hill and the engine light come on. once i was over the pass the light went off. During my 4 wheelin' trip it never came back on until I was headed home and going over another pass and then it stayed on for a couple of days. I had it checked and it was a cylinder 5 misfire. I did some research and found that replacing the coil cover might fix the problem and if not the spark plugs would need to be changed.
I changed the coil cover, problems solved... until I headed to the mountains. light came on and then eventually went off later that day. I didnt think much of it. then a few months later i was headed to the mountains again and the light came on in the same place on the steep incline hill. I. took it back to the shop, same reading. I decided it was time to replace the spark plugs anyways so I would invest. I have new plugs and everything is good however, I had no plans to go to the mountains in the near future. Now, a few months later I headed to the mountains and crossed my fingers it would not come on but it did.
I've done the research again and it seemed like the coil cover and spark plugs are usually the cause of the problem...however I have changed mine. The light is now off again. I don't understand what is triggering the problem and what is really happening and if it is safe to keep taking to the mountains with this happening. I did notice that everything was fine at 60MPH but once i hit the hill and steeped on the gas to go 65 and hit 4-5RMP that is when the check engine light came on...
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