$3 O2 simulator fix for P0420 Check Engine Light
Trki, Kody, Cheaty do
Do you occasionally get code P0420 - catalytic converter low efficiency? This $3 electrical circuit may fix the problem permanently by electrically smoothing out the o2 sensor output. Don't spend $10 on fuel additives (tried it), or $100 on new o2 sensors (tried it), or $200-400 on a new non-OEM catalytic converter which may fail again (seen lots of posts by Honda owners who say they don't last). You'll see how to test both o2 sensors on a bench with a propane torch - if either has failed you should replace it and see if that fixes the problem. I replaced mine before I knew how to test it and it solved the problem for a short while but it came back. If you have a graphing ODB scanner I show how to graph the o2 sensors to see if the catalytic converter is working. You can try simpler ODB readers such as ScanGuage but the data is supposed to change from 0V-1V every second so you really need a graphing tool (Harbor Freight 98614 / 60693 is $120 but often $80). I also tried to use a multimeter hooked into the o2 sensor with wires but I found that also too hard to really see what's happening. Once you verify from the o2 sensors that the catalytic converter isn't functioning efficiently, I show you how to modify the downstream sensor #2 mounted on or after the catalytic converter with a simple Resistor Capacitor (RC) low-pass filter to smooth out the signal by removing "high frequency" (faster than 5 seconds) changes in the o2 levels . There is an alternative using spark plug defouler/unfouler to pull the o2 sensor back from the exhaust stream, but it's unclear if this will work or for how long. The computer P0420 is strictly determined by whether the downstream sensor #2 is crossing the .5V threshold a lot less than sensor #1, so an electrical solution addresses this directly. This method may not work if your o2 sensor is too far gone, in which case you can buy a 555 timer based o2 simulator which generates a signal independent of the o2 sensor output, but that costs $20-40 and you have to mail order it. This $3 solution is easy if you're good with a soldering iron and worth a try. Here's a link to one of the internet posts on how to build the RC low-pass filter: http://www.wazees.com/media/4324/02-mil.pdf Here's a video about o2 sensors and P0420 but I tried his diagnostics and they were difficult. He uses a basic OBD scanner and it's just not quick enough. It encouraged me to buy the graphing scanner and I'm glad I did so I could verify my fix works, although you don't have to. He also tried diagnosing it with the temperatures, which I also did, but my results were inconclusive: http://www.youtube.com/watch?v=9VZ5K8n5jj0 Here's an excellent video on how to bench test an o2 sensor. If yours is bad I think you want to replace it, especially if it's the upstream sensor since that's going to affect how rich/lean your engine is and may cause damage to a catalytic converter. If it's the downstream sensor that's broken then my fix may work on it - it depends on how it's broken. o2 sensors cost $100, and this fix is a lot cheaper than replacing the sensor, so I'd try this before replacing the downstream sensor. http://www.youtube.com/watch?v=stFhLSHsOGg Finally here's an excellent video on how to use the spark plug defouler/nonfouler. My biggest gripe is that I couldn't find any reports on the internet to support that this actually works most of the time or that it lasts. Some of you who are more comfortable with a drill vs soldering iron might want to go this route. You can find the parts at Autozone for $10. I suppose if you mail order them you can maybe do it for $5. Half my motivation for doing this DIY is because mail ordering parts (spark plug defouter or 555-based o2 simulator) is inconvenient. http://www.youtube.com/watch?v=GqDmmLQ4pGk
Komentarze
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I tried this but with the resistor on it was giving me 1.25 volts which my other bank sensor is only giving me .75 so I got a new code. I took off the resistor and it dropped it to .75 only time will tell if the CEL comes back.
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so if you dont have to have a sniffer test in the state your in you could do this trick and hollow out your cats?
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It worked perfect for my 01 Honda civic.
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the wires are stainless steel .. that is why is so difficult to solder.
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Your capacitor says AXIAL leads. The one I bought says RADIAL leads. Does that matter?
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So what a lot of people don't realize and I know only because I have been a license smog tech for about 18 years now is the rear sensor is not only to monitor the catalytic converter, but to also fine tune fuel trim. This is only good for someone who is trying "beat" the system. It's not a great or smart choice for your car. Also it's kinda illegal to tamper or modify your emissions on a car. That may be a whole other thread or video but you should know.
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can someone explain exactly how this works? what is capaciter doing?
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how about a close up picture of the cap and resistor all wired up but not taped
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Nice video, what is techron on time 1:52?
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Soldering wires on an O2 sensor is difficult or impossible because the conductor is made of stainless steel, not copper. It's really the only place on a car that you will see steel conductor material, and it's there to withstand extreme heat. This is why you see 'universal' oxygen sensors come with crimp connectors. Also, keep in mind that oxygen sensors breathe through the signal wire to obtain their atmospheric oxygen reference, so don't crimp or melt the insulation and don't use shrink tubing lined with hot glue. Water ingress is unlikely and quickly evaporated due to the heat and stainless steel will not corrode so using an unshielded butt connector is completely acceptable.
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I did this on a 2002 Toyota Sienna. It had p0420 code before. After modification it gave p0136. I figured out that this video is not correct for all vehicles, the Toyota sensor required the resistor be put on the signal ground wire (the white one). Not the blue one as shown in this video. After moving the resistor to the white wire this was a total success, it's been 300 miles and no codes.
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4.7 uF was actually too high for me. I eventually got P0137, P0138, and P0139 codes indicating the o2 sensor wasn't working "fast" enough. Had to swap it out for a lower 1uF cap.
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Hi, does it make a difference where on the wire its done at? Can I do this up closer by the harness? I have no room down at the bottom by the o2 sensor... A fast reply would be greatly appreciated.
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what would be the result of using a 10 ohm 1/2 watt resistor and the same capacitor you've used here? I just had one on hand and I'm not electrically savvy to know if it'll be okay
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MITEEman, what happen if the resister and/or capacitor burn for some reason? Should I able to start the car?
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http://home.earthlink.net/~jcgebhart/o2sens.html
I tried this and mine jumps alot. does it need a smaller resister to make it smoother on the graph? -
MITEEman, if you please iwould like to ask you about 1- why did you say that this modification is for offroad use only? 2- a bad catalytic converter causes increased fuel consumption, will that modification improve the fuel consumption or it just eliminates the CEL. 3- in my country there is no smog test also cars use only one catalytic converter, my car is imported so it has 3 catalytic converters (california emmissions Jeep cherokee xj 2001 4.0L) my question is if i replaced the two pre-cats with two pipes and applied your fix(RC), would it work with out triggering the CEL, and would that affect the fuel consumption? Thanks in advance
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MITEEman, I really appreciate the time you took to create & share this video, and providing help to those of us with this error code on our vehicles... And on that note, I would like to ask/confirm with you the wiring setup on my 2009 Honda Pilot, as I plan to do this work to it. the color wiring I have does not match the ones on your video, I have 2 white, a black, & a grey wire. From what I've read the 2 white wires are the heater, black is positive signal and grey is negative. And the resistor (does not matter the direction) should splice between the black wire and the capacitor negative lead to contact the grey and the other capacitor lead should connect to the resistor opposite the end of the sensor. Is this correct?
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will this work on late model cars say a 2012 dodge challenger?