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LeeADAB

The Old P0430 Chestnut

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Can anyone give a reason why I get a P0430 code. I know it is a bank below efficiency problem code. Just that I've had both upper sensors replaced in the past and for years I have randomly had this code turn on the warning light.

It doesn't affect fuel economy and hasn't shown up for about a year now.

Today I had the Battery out (to fit my new interior and exterior temp sensors) and this now means the car is in learning mode again?

Is there something that I need to do?

In the past I cleaned the MAF sensor but not replaced. If it were a problem it would happen more often? It used to happen when I did a longer journey which I thought was because I usually do short trips.

I read years ago that the ecu thresholds were set to close together and that a slight fluctuation would set this code.

Or that it is the CAT but fail to believe that and nearly everything I read about others having CAT replaced say it throws the code after replacement.

Any advice or anyone else had this problem?

I'm not worried as it has happened for years on and off but would like to see if I can stop it from happening.

Cheers, Lee

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In May 2005 Toyota released a technical service bulletin ( EG-5010 ) relating to P0420 or P0430 fault codes appearing on Rav4's usually after driving for a longer than usual trips, the basic issue is over lots of shorter trips the catalyst slowly fills with particulate matter this slightly reduces the catalysts cleaning ability but it remains within tolerances ,the ECU learns this reduced efficiency. However after a long trip where the cat gets red hot for long periods the particulate matter is burned off and the efficiency of the catalyst suddenly increases before levelling off and then decreasing again the ECU detects this sudden increase which it believes is a fault and puts the EML lamp on.

To fix this Toyota modified the manifold catalyst unit with a different internal surface coating to reduce the build up of particulate matter & modified the engine ECU software with wider monitoring periods to ignore sudden changes.

The ECU needs to be programmed with the latest software version available and a modified catalyst part number of at least 25051-28041 or later needs fitting.

Devon

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Thanks Devon that's really helpful info.

So if I just reset the light as I have done for years I should save a fortune on buying a new CAT and a software update. Which I imagine will cost a pretty penny. More than a few moments of my time erasing the code.

Shame they didn't say that when it was diagnosed by mr.T before warranty ran out in late 2005 early 2006. I was told p0430 would need a new air flow meter if it came back. Since then I just cleared the code as everything i'd read said that there was no confirmed fix. It comes on so rarely and doesn't affect emissions test during MOT.

The main concern would always be if the MIL lamp came on during the MOT as they don't like them on during testing. Not sure if it would fail though or just be an advisory that the lamp was on?

Thanks, Lee

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Clearing the fault code will do no harm just make sure its P0420/430 and not another issue, at present an EML light on is not an MOT issue however new guidelines are coming and it will be a failure eventually. If the cat hasn't suffered any damage then reprogramming the ECU can help and shouldn't cost more than an hours labour to complete.

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In May 2005 Toyota released a technical service bulletin ( EG-5010 ) relating to P0420 or P0430 fault codes appearing on Rav4's usually after driving for a longer than usual trips, the basic issue is over lots of shorter trips the catalyst slowly fills with particulate matter this slightly reduces the catalysts cleaning ability but it remains within tolerances ,the ECU learns this reduced efficiency. However after a long trip where the cat gets red hot for long periods the particulate matter is burned off and the efficiency of the catalyst suddenly increases before levelling off and then decreasing again the ECU detects this sudden increase which it believes is a fault and puts the EML lamp on.

To fix this Toyota modified the manifold catalyst unit with a different internal surface coating to reduce the build up of particulate matter & modified the engine ECU software with wider monitoring periods to ignore sudden changes.

The ECU needs to be programmed with the latest software version available and a modified catalyst part number of at least 25051-28041 or later needs fitting.

Devon

It is knowing we have the facility of replies like this to problems that will keep me driving Toyotas for a long time to come......good wan Devz min.

Big Kev

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Couldn't agree more Big Kev!! :)

Really helpful info from Devon too. Thanks for your response!!

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Lee, I had / have the same problem, same car same year, and only after a long run, and then only occasionally. Now the light is on permanently. As with you no detriment to performance or economy, just a nuisance really!

The mod suggested by Devon would appear to be the answer, but would it be sensible to get an expensive modified catalyst from a breaker, or spend a lot of cash on a new one!

My car is here in Spain, so tomorrows job will be to visit Mr Spanish T for a quote for the ECU software, but is it also necessary to do both jobs, or will just the update suffice?

Devon, thanks very much for a great reply!

Ainsley

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So gents,

Bought myself a nice looking 2001 Rav4 this weekend in the south of France, 100,000km one owner for the last 10years, seemed a good car.

Just after a refuel at about 250km the check engine light came on! (I had initially thought it may have been a fuel issue) but went to the garage this morning and got P0430 and PO420 codes.

The garage think lambda sensors (two have been changed already)... but after reading the above, I'm not so sure..

The car used to just run to the marina and back, so what Devon mentions about long trips seems to ring true...

So, wanted to ask...

- is there any way to check if it's sensors or ECU?

- if I ask them to clear the code, and it is an ECU issue, will the problem re-occur

- if the ECU reprogram is a must do... do i also need to do the CAT

David

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Hi David,

I wouldn't spend out on sensors personally. I've had two go over the last 8 years and you will get separate codes each of the four sensors.

I don't get the p0420 code so not exactly the same as you. My MIL lamp has come on only ONCE this year with the p0430 code. I just attach a code reader to confirm that is the code and clear it. For the sake of a £20 device you can at least get an idea of what is wrong rather than spending out on diagnosis.

I'm not going to Shell out for a new/salvage CAT just to stop the light coming on once/twice a year.

I wonder if Toyota can tell us if the ECU has had the "patch" without actually plugging in the car to read the firmware/version? Maybe they have that info logged?

How did you get on Ainsley with the ECU update. Was yours up to date? Light now gone for good?

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I ended up changing all the lambda sensors and since then no light!! However the 0420 and 0430 codes are now showing, and the next thing to do will be to visit my friendly local garage, which has the right test equipment. The light is intermittent, sometimes on for only a few days, and there is no pattern to it!!

So temporarily back to the drawing board, as it could just as easily be a wiring issue. We won't know till the exhaust test has been done, so will report back later!

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My equally friendly local garage had the car for a day, spoke to Toyota, cleared the code, and tells me he’s pretty certain he needs to change two of the sensors (Toyota also said to change the Cat, but he said to ignore that).

Handed the car back (free of charge!) and said to drive around for a few days, see if the light came back on, and on the way back from work today, after around 60km, the light popped up again.

He’s quoting 600euros for two sensors and the work, which is probably pretty comparable.

I’m pretty sure that seeing as the light came back after only relatively short drives to work and back that it’s not going to be an ECU issue (fair to say??).

Just might need to put a little cash aside for the repair.

In the meantime I’ve also ordered a reader, to check the codes when they come up.

David

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Hi David,

Looking at your post again, the 0420 0430 codes are the Cat performance codes, and the Lambda sensor ones are different. I originally got the lambda codes for the top bank, and on Anch's advice changed all the sensors. One was cross threaded and that was another story! We drove back to UK through France, and 3/4 of the way down, the 420 430 codes came up. I assume that as the lambda sensors were now working properly, that a weakness was being found in the cat sensing system, because it seemed strange that they should both suddenly fail at the same time.

Is your friendly man looking at changing the lambda or the cat sensors? An exhaust gas test will tell if the cat has failed (possibly plus the nasty egg smell) If that is ok, then it should be the sensors, or a wiring issue. I bought the lambda sensors in UK, Denso which are the OEM for Toyota, and paid around £75 each. Fitting was easy, so €600 for two lambda sensors sounds expensive! I haven't looked into the price for the cat sensors yet, and will do that in UK, when we are back for Christmas.

One thing for certain, I don't like having the light on, even though I think all is actually OK. My Spanish MOT isn't due till next July, so plenty of time to sort it out!!

Ainsley

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I don't think there are any more sensors to change. Just the two pre-cat top AF sensors and two post-cat bottom O2 sensors.

My exhaust emissions have always been fine so I doubt the cat is an issue. No codes for the other sensors either so would imagine that it is just the tight variables in the original ecu. I will contact my local toyota garage when I get a mo to ask if they have records on what ecu version I am on. If not I'll also get a quote to have it updated. Problem is mine is so rare that I may not know if it has made a difference for a while.

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So, if there are no more sensors, apart from the lambda sensors (two up two down) then how does the system sense that the cat values are below par? Haven't had a chance yet to get my exhaust tested yet, must do it next week!

Confused now, in sunny southern Spain

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I think that the two post cat sensors under the cat give the ecu that info?

I think there is another smaller cat further along the exhaust but don't think there are any sensors to monitor that one.

Ps. Sunny Spain sounds great!!

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Update: Garage have checked the ECU version as requested and it was up to date. There are no more updates for it.

I was advised that if I am happy to continue clearing the code then that is fine. Especially as the car runs perfectly and I know the reason why the P0430 code gets triggered.

IF the MIL starts to show more often than the current once/twice a year AND it becomes an MOT failure then that is when I will consider a new CAT or an updated salvaged one.

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Latest! The 0420/0430 has again been on, but after a short run again the light went off! Any way, when it's next on, will get a gas test. As for the fuel pump, sorry but nothing heard from our 2003 4.2. Just had the 150000 km service, and asked them to check for pump noise, and nothing found. Need new pads all round however, so next trip, back to UK for supplies!!!

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There are 2 sensors in the manifold and 2 sensors on the other side of the cat in the exhaust. See fig. 6 here;

4.3 oxygen sensor location.pdf

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Cheers Ainsley. Keep us informed with any news. It seems that it is right not to hear the fuel pump which explains why others can't hear theirs either.

Quote: "fuel pump only works while cranking or the engine is actually running"

Although everything else I could find said to listen for the fuel pump to prime and I really thought I'd heard that before.

Lucky I didn't lay bets on that one!

It's not like I haven't had it long either - 8yrs.

Cheers, Lee

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My little Daihatsu definitely primes for a few seconds when I switch the ignition on.

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I keep getting this code as well. I can clear it easily with a code reader. My local garage agrees there is nothing actually wrong but says i need to take it to a dealer to get the software fixed. If I dont he will charge me next time I take it in for repair ( even if he cant fix it )

Long distances and costs are preventing me from doing this straight away. Is there a DIY fix to stop this spurious error message coming up.

No MOT out here so a Cat convertor isnt vital

thanks

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