catalyst efficiency below threshold P0422
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
catalyst efficiency below threshold P0422
Greetings, A check engine lite came on on my 2008 S550. Within a day it went out by itself but I decided to check what the code was. My icarsoft scanner tells me that I had code P0420, catalyst system efficiency below threshold bank 1. I cleared the code and drove about 90 miles and checked it with my scanner. I now have pending code P0422 left and right bank. On my scanner I look under "catalyst monitor" and it provides the following for bank 2: test is 3928, min is 4096 and max is 65533 and for bank 1: test value 3228, min 3288 and max is 65535 - both bank 1 and 2 test values are below the acceptable range (anyone know what units are these numbers?) . My gas cap is tight, air filter is clean, car uses about a quart every 5000 miles, No misfires, car runs great and gas mileage hasn't changed and is within spec. The scanner also tells me that my 02 sensors 1 and 2 on both banks are within spec. Where should I start? Thanks for the help!!
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2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
I get the same code on my car when I use less than 93 octane although my car is an S600 with a V12. I add a can of Techron on the first of every month and that stops the code dead. Also steady highway driving also cures the code but it will return intermittently in city driving. Use a high grade fuel and run it on the highway at speed a little more. Good luck.
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on older Mercs it was normal for the CAT to collapse internally and strangle the engine - not really heard of this on a W221, but the v12 is designed for multimillionaire's to use for 3 days a year, and throw away after 2 years... where running costs were never a factor.... who knows....
just as likely its only ever rev'ed to a spike of 1200 rpm - whereas in Germany the idea is to never let it drop below 4000 as you try to swat peasants off the autobahn. May as well run some CAT cleaning compound through a few times and try ragging it to death when warmed up. You might get picked up on military radar trying that in the USA though
just as likely its only ever rev'ed to a spike of 1200 rpm - whereas in Germany the idea is to never let it drop below 4000 as you try to swat peasants off the autobahn. May as well run some CAT cleaning compound through a few times and try ragging it to death when warmed up. You might get picked up on military radar trying that in the USA though
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
Thanks vettebk...I'll try the techron. 93 isn't available where I live here in Denver. Our premium is 91 which is what I've been using. I'll get it out on the highway and run it some and report back.
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
Thanks Botus. It is true...I bought it for my wife and I'll bet it rarely gets above 1200 rpm. Sound like I need to have more fun with it! What do you mean by "ragging it to death" ? I have some cat cleaner I just got. I'll give it a go. Thanks again!!
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
Thanks Ninamashr! I just got some and its sitting on my workbench waiting for the fuel level to go down. How many treatments did you do and how much did you put in?
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Ragging to death is a UK expression for once (ideally) you've got to full operating temp with 10mile drive or so, use every last bit of its performance. Maybe "drive it like you stole it" translates more easily
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Remove seal before emptying entire contents of one bottle of Cataclean® Petrol into fuel tank. Then drive for at least 15 minutes and refuel when necessary. Recommended ratio of one 500ml bottle of Cataclean® Petrol to approximately 15 litres of fuel.
Mine has a 90ltr tank (that massive), many little cars are under 50 these days, with 70 being a big tank. Oh, 15 litres a bottle, that about 4 of your gallons 3.7 ltr per US gallon.
I think the "ragging" bit must come from a dog killing its toy rag doll prey,
...
Mine has a 90ltr tank (that massive), many little cars are under 50 these days, with 70 being a big tank. Oh, 15 litres a bottle, that about 4 of your gallons 3.7 ltr per US gallon.
I think the "ragging" bit must come from a dog killing its toy rag doll prey,
...
Last edited by BOTUS; May 23, 2021 at 09:44 AM.
Thread Starter
Junior Member
Joined: Nov 2015
Posts: 50
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
Remove seal before emptying entire contents of one bottle of Cataclean® Petrol into fuel tank. Then drive for at least 15 minutes and refuel when necessary. Recommended ratio of one 500ml bottle of Cataclean® Petrol to approximately 15 litres of fuel.
Mine has a 90ltr tank (that massive), many little cars are under 50 these days, with 70 being a big tank. Oh, 15 litres a bottle, that about 4 of your gallons 3.7 ltr per US gallon.
I think the "ragging" bit must come from a dog killing its toy rag doll prey,
...
Mine has a 90ltr tank (that massive), many little cars are under 50 these days, with 70 being a big tank. Oh, 15 litres a bottle, that about 4 of your gallons 3.7 ltr per US gallon.
I think the "ragging" bit must come from a dog killing its toy rag doll prey,
...
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mate on his little pug 1.0 ltr he only chugs round local trips, nearly failed his MOT emissions test (annual roadworthiness check) mechanic said to use cataclean….. ( I think he actually had one of these smoke and mirrors https://www.terraclean.co.uk/ guys do a home side clean first - when he noticed it drive much better afterwards (about $100 I think), then uses cataclean two times a year and moved from budget to branded petrol, 2 years on his emission are better than they had been for 5 years.
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From: Lakewood Colorado
2008 S550 4matic, 2001 e320 4matic (Sold), 1999 CLK 320, 1982 380 SL
Update...
Greetings, A check engine lite came on on my 2008 S550. Within a day it went out by itself but I decided to check what the code was. My icarsoft scanner tells me that I had code P0420, catalyst system efficiency below threshold bank 1. I cleared the code and drove about 90 miles and checked it with my scanner. I now have pending code P0422 left and right bank. On my scanner I look under "catalyst monitor" and it provides the following for bank 2: test is 3928, min is 4096 and max is 65533 and for bank 1: test value 3228, min 3288 and max is 65535 - both bank 1 and 2 test values are below the acceptable range (anyone know what units are these numbers?) . My gas cap is tight, air filter is clean, car uses about a quart every 5000 miles, No misfires, car runs great and gas mileage hasn't changed and is within spec. The scanner also tells me that my 02 sensors 1 and 2 on both banks are within spec. Where should I start? Thanks for the help!!
Even though all the O2 tests said my O2 sensors were within spec. I decided to replace the downstream O2 sensor on the right bank (bank 1) and see what happens. I hate throwing parts at a problem but figured it was far cheaper than taking it to my inde for an hour diagnostic charge. The readings went from +/- 3200 to over 6000 which is higher than any reading I had since this issue started so I think the problem was a "weak" O2 sensor. As a replacement, I used a Bosch sensor 16747 ($62 on Amazon...delivered the next day. The Mercedes sensor is $318 retail, $236 at Suburban parts). Be sure to get the sensor that fits both the right and left size as I believe the one specific left or right size has a different wire length. It was relative easy to replace...took off the front and back under-pan and had clear access with a crescent wrench and a cheater (long pipe for leverage). The connectors are located on clips mounted to the back of the engine. Open hood, remove air cleaner and unplug oil centrifuge rubber hose for better access, remove the connectors from the connector spring clips that are mounted on the back of the engine for the upper and lower o2 sensors and there is enough cable on the rear sensor to pull it's connector up through the engine bay to place both hands on the connector to disconnect it. Be sure to screw the new o2 sensor into the cat. prior to connecting the connector as the wire will twist if you don't. For reference the car has 150,000 miles and runs perfect (before and after the O2 replacement, averaging 19 MPG the last 5000 miles. Thanks to all who replied with ideas!!
I still don't know what the readings are...are they some sort of an oxygen count? anyone know?
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CAT sensors are strange things - they actually have a heater circuit this is the usual bit to fail, and I only found out on a bike forum this year, a little 1mm diameter air bled hole on the outside to let fresh air in so it can compare the madness
