SwedeSpeed - Volvo Performance Forum banner
1 - 20 of 38 Posts

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #1 ·
CEL came on last night after about 30 minutes of slow driving in a snow storm. PCM Scan reported this:<br>P0420 Catalyst system below Efficiency Threshold (Bank1)<p>I collected some data from vaiours PIDs (MAF, ECT, Lambda, Catemp11, etc) and I didn't see anything out of the ordinary.<p>She seems to be running find (feels okay, sounds okay) so anyone know what might cause this DTC?<p>LTA<br>
 

·
Super Moderator
Joined
·
9,305 Posts
Re: (chinaonnitrous1)

Bank 1 is the front sensor, on the manifold.<p>I'd drive it and see what happens. Might just be due to the cold/wet and a temporary bad signal.<p>Tom.
 

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #4 ·
Re: (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">Bank 1 is the front sensor, on the manifold.<p>I'd drive it and see what happens. Might just be due to the cold/wet and a temporary bad signal.<p>Tom.</TD></TR></TABLE><p>Thanks for the clarification, Tom. Bank 1 is the front which is also known as 'Wide Band O2' from a generic OBD2 perspective, which is also where "cattemp11' singal comes from, right? Isn't this O2 sensor located after the turbo and before the cat? (Ie not right on the manifold?) Just want to be clear on this but also asking because I want to collect data from the sensor respnsible for this errant and/or out of spec value (if that's what caused it).<p>Summing it up, she's running fine and I haven't bothered to clear the DTC. I assume this type of DTC will not clear on it's own, right? <p>LTA<br>
 

·
Registered
Joined
·
1,261 Posts
Re: (LTA)

Same problem here. Using the SVR down pipe. Only started occurring lately. I noticed that the code is thrown only when I rev above 3000rpm when the oil temp has not exceeded 65degC or 149degF...i.e. engine is still cold. No issues once car is properly warmed up.<p>I take it that the CAT is getting old and running less efficiently or that one of the O2 sensor has seen better days.<p>No effect on engine performance, but if the code is thrown often enough, I get an engine check light. Never bothered about it as my auterra is able to clear the code.
 

·
Registered
Joined
·
438 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (Bank1)" (LTA)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>LTA</b> »</i></TD></TR><TR><TD CLASS="quote">CEL came on last night after about 30 minutes of slow driving in a snow storm. PCM Scan reported this:<br>P0420 Catalyst system below Efficiency Threshold (Bank1)<p>I collected some data from vaiours PIDs (MAF, ECT, Lambda, Catemp11, etc) and I didn't see anything out of the ordinary.<p>She seems to be running find (feels okay, sounds okay) so anyone know what might cause this DTC?<p>LTA<br></TD></TR></TABLE><p>P0420 = ECM-4801<p>Diagnostic trouble code (DTC) information<p>Condition<p>The control module continuously checks three-way catalytic converter (TWC) efficiency by comparing signals from the rear heated oxygen sensor (HO2S) with the front heated oxygen sensor (HO2S). Diagnostic trouble code (DTC) ECM-4801 will be stored if the efficiency of the three-way catalytic converter (TWC) deviates too much.<p><br>Substitute value <br>Rear heated oxygen sensor (HO2S) control is disabled.<p><br>Possible source<p>-misfiring<br>-air leakage in the intake system<br>-air leakage in the exhaust system<br>-faulty fuel pressure<br>-uneven compression<br>-defective three-way catalytic converter (TWC).<p><br>Fault symptom <br>-malfunction indicator lamp (MIL) lit.
 

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #7 ·
Re: DTC P0420? "Catalyst system below Efficiency Threshold (EBender1965)

Test<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>EBender1965</b> »</i></TD></TR><TR><TD CLASS="quote"><p>P0420 = ECM-4801<p>Diagnostic trouble code (DTC) information<p>Condition<p>The control module continuously checks three-way catalytic converter (TWC) efficiency by comparing signals from the rear heated oxygen sensor (HO2S) with the front heated oxygen sensor (HO2S). Diagnostic trouble code (DTC) ECM-4801 will be stored if the efficiency of the three-way catalytic converter (TWC) deviates too much.<p><br>Substitute value <br>Rear heated oxygen sensor (HO2S) control is disabled.<p><br>Possible source<p>-misfiring<br>-air leakage in the intake system<br>-air leakage in the exhaust system<br>-faulty fuel pressure<br>-uneven compression<br>-defective three-way catalytic converter (TWC).<p><br>Fault symptom <br>-malfunction indicator lamp (MIL) lit.</TD></TR></TABLE><p>Wow, thanks for the x-ref on the DTC. Very helpful! <p>I take it this : "Substitute value <br>Rear heated oxygen sensor (HO2S) control is disabled." means I should clear the DTC to get back to normal for better economy/emmissions control??<p>Was that x-ref/lookup down with Vadis?<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>blot</b> »</i></TD></TR><TR><TD CLASS="quote">Same problem here. Using the SVR down pipe. Only started occurring lately. I noticed that the code is thrown only when I rev above 3000rpm when the oil temp has not exceeded 65degC or 149degF...i.e. engine is still cold. No issues once car is properly warmed up.<p>I take it that the CAT is getting old and running less efficiently or that one of the O2 sensor has seen better days.<p>No effect on engine performance, but if the code is thrown often enough, I get an engine check light. Never bothered about it as my auterra is able to clear the code.</TD></TR></TABLE><p>Thanks for the info, blot. Glad to know I'm not alone on this one. I'm pretty sure the SVR and Ferrita DP use the same race cat and I think we noth use A-mist (although mine is a 'little' more tame than yours). Contrary to your thoughts I'm thinking the cat might be too efficient (mine has 28K Km/17K miles on it, ie it's not very old). These nice 3" DP with high flowing cat's really get the heat out faster than the stock DP, this could be a big factor.<p>So I wonder if this means the race cat is fine and simply puts the system outside of expected/OEM paramaters, or if in fact there is a problem with the cat.<p>LTA<br>
 

·
Registered
Joined
·
2,074 Posts
Re: (blot)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>blot</b> »</i></TD></TR><TR><TD CLASS="quote">Same problem here. Using the SVR down pipe.</TD></TR></TABLE><br>One thing that OEM engineers have to worry about and that the aftermarket can (perhaps) ignore is cold-start emissions. A lot of engineering is focused on getting some emissions-conversion efficiency out of of the cat as quickly as possible after a cold start. This includes special formulations and attention to the physical dimensions of the exhaust system and "brick".<p>The aftermarket is only focused on reducing backpressure. These goals can be in conflict. If emissions-convertion efficiency falls below a certain threshold, a CEL will be thrown. It's possible that the poorer cold conversion efficiency of the "race" cats are tripping the cat monitor. The colder the ambient, the more likely this is to occur.<p>Just guessin' <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0">
 

·
Registered
Joined
·
438 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (LTA)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>LTA</b> »</i></TD></TR><TR><TD CLASS="quote"><p>Was that x-ref/lookup down with Vadis?<p><br>LTA<br></TD></TR></TABLE><p>YES!! That is the VADIS Diagnostic Info for that ECM Error Code. VADIS also has the OBD II Cross eferences to their ECM Codes.
 

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #10 ·
Re: DTC P0420? "Catalyst system below Efficiency Threshold (EBender1965)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Dyno</b> »</i></TD></TR><TR><TD CLASS="quote"><br>One thing that OEM engineers have to worry about and that the aftermarket can (perhaps) ignore is cold-start emissions. A lot of engineering is focused on getting some emissions-conversion efficiency out of of the cat as quickly as possible after a cold start. This includes special formulations and attention to the physical dimensions of the exhaust system and "brick".<p>The aftermarket is only focused on reducing backpressure. These goals can be in conflict. If emissions-convertion efficiency falls below a certain threshold, a CEL will be thrown. It's possible that the poorer cold conversion efficiency of the "race" cats are tripping the cat monitor. The colder the ambient, the more likely this is to occur.<p>Just guessin' <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> </TD></TR></TABLE><p>Nice guess <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> Show off <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>I'm sure you are spot on <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0"> I was thinking that too but I had some trouble somewhere between the keyboard and the chair <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0"> <p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>EBender1965</b> »</i></TD></TR><TR><TD CLASS="quote"><p>YES!! That is the VADIS Diagnostic Info for that ECM Error Code. VADIS also has the OBD II Cross eferences to their ECM Codes. </TD></TR></TABLE><p>Brilliant! Never knew all the DTC info is just sitting there waiting. Thanks, will do my own look-up next time.<p>LTA<br>
 

·
Registered
Joined
·
1,261 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (LTA)

I still believe that it is the CAT that is dying. I never had the code with the SVR DP for a good 3.5years, until recently. I just had a look at the internals of the CAT (which is a random tech metal cat), and it looks ok, but I guess the properties of the CAT have deteriorated.
 

·
Registered
Joined
·
2,074 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (blot)

As I understand it, cats do "age". They get poisoned by the crap they ingest over the years and efficiency slowly goes down. The OEM engineers have to spec out the cat and set the monitoring thresholds with end-of-life efficiencies in mind. I've never heard of it being a problem in the aftermarket, but...
 

·
Super Moderator
Joined
·
9,305 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (Dyno)

Yes, they do and you can read the aging metrics out from the system.<p>The problem with replacement performance cats is that they are different from the stock cat in their efficiency and response. The rear O2 sensor is a crude instrument, capable only of sensing whether the mixture is "going lean" or "going rich", i.e. it can detect the crossing but not the absolute value.<p>The front O2 sensor on the other hand can measure the mixture precisely, and that's exactly what it does for the ECU. The ECU uses it for fine control, and the rear one for trending and catalytic converter operation. But, it does this by comparing the front to the back, with values as would be expected from stock hardware. If you change the hardware, you change the response, and if that response wanders out of margin, you get a CEL.<p>The CEL in itself isn't the problem. The problem is that a) the car will fail inspection since it's signalling a fault and b) the car stops trusting its sensors, meaning it goes into a single-sensor mode (which can't adapt), open-loop mode (which is inefficient and smoggy), or limp mode (which nobody wants). This is why cat selection is so important to a tuner.<p>Tom.
 

·
Registered
Joined
·
2,074 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (tmtalpey)

Back in the day, us kids used to take our parent's hand-me-down cars and imediately slap on a set of headers and glasspacks. Nowadays, it's a chip and a downpipe (with free-flowing cat). It's been a few years now and there must be a lot of cars our there with "race" cats and OBD electronics.<p>Has anyone heard of catalyst monitoring CEL's showing up after a long period of bliss? Have we uncovered a trend or are these isolated incidents?
 

·
Registered
Joined
·
872 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (Dyno)

This is also the code that you will get from time-to-time if you have no catalytic converter at all (unless you use an O2 extension fitting).I think it just means that the rear sensor is not warming up completely, but the car still runs fine.<p>P.S. Where are the code tables in VADIS? I never noticed them...
 

·
Registered
Joined
·
2,074 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (jrgoffin)

EPA has demanded that the CEL be lit if the catalyst in missing or not fuctioning properly. There is a bit of software in the ECU that looks at the difference between the pre-cat O2 sensor and the post-cat sensor. If the catalyst is working as it should, there WILL be a difference. There is a limit for how little difference can be tolerated before the CEL comes on.<p>I don't think we're discussing faulty sensors. In this case, the sensors could be reporting the truth: the cat is not working as expected.<p>As you correctly state, this is the code you get when use the Sawzall to ditch the cat. This is exactly what the algorithm is trying to detect and exactly what the EPA had in mind when they wrote the regs.<p>"Running fine" means one thing to us hot-rodders but something very different to your government!
 

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #17 ·
Re: DTC P0420? "Catalyst system below Efficiency Threshold (Dyno)

Looks like RalliTECK (IPD) might have the answer: <A HREF="http://www.rallitek.com/rao2sesp.html" TARGET="_blank">http://www.rallitek.com/rao2sesp.html</A><p>Google Search is working well this morning <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> <p>LTA<br>
 

·
Registered
Joined
·
2,969 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (LTA)

I have one of these on my car and have never thrown any codes it was added at the time of install <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0"> there is a place online that has them for like $10 per other swedespeed members but I don't know the site.
 

·
Registered
Joined
·
2,545 Posts
Discussion Starter · #19 ·
Re: DTC P0420? "Catalyst system below Efficiency Threshold (volvosince16)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>volvosince16</b> »</i></TD></TR><TR><TD CLASS="quote">I have one of these on my car and have never thrown any codes it was added at the time of install <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0"> there is a place online that has them for like $10 per other swedespeed members but I don't know the site.</TD></TR></TABLE><p>volvosince16: You are correct and I think I found the one you're refering to. Is this the one you installed?<p><A HREF="http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=390048337699QQssPageNameZMERC_VIC_RCRX_Pr4_PcY_BIN_Stores_IT&refitem=220401029471&itemcount=4&refwidgetloc=closed_view_item&usedrule1=CrossSell_LogicX&refwidgettype=cross_promot_widget&_trksid=p284.m183&_trkparms=algo%3DCRX%26its%3DS%252BI%252BSS%26itu%3DISS%252BUCI%252BSI%26otn%3D4" TARGET="_blank">http://cgi.ebay.ca/ws/eBayISAP...n%3D4</A><br>eBay seller is "sfconsignments"<br><IMG SRC="http://img.auctiva.com/imgdata/0/9/0/2/3/8/webimg/117633440_o.jpg" BORDER="0"><p>LTA<p>
 

·
Registered
Joined
·
2,621 Posts
Re: DTC P0420? "Catalyst system below Efficiency Threshold (LTA)

That should work, well at least not throw a code as long as the B1S2 heater circuit is good. Its considered emissions tamper though.<br> <br>Basically all those bung extensions do is to pull the rear O2 sensor (or for reference B1S2, there is only one bank in the 5cyl, B1S1 is the front) out of the exhaust stream. By doing this, the rear O2 sensor gives a very low reading of O2 to the ECM which is interpreted as the Catalyst having good efficiency. Remember low O2 reading on the back side of the cat means that all the O2 was used up burning off any HC and CO emissions.
 
1 - 20 of 38 Posts
Top