P0420 and P0430 codes coming and going. Why? Please!

[crussell]

Hi everyone

weve owned our RAV4 for a few years now. The engine management light came on beginning of this year after a major service. It stayed on giving these faultcodes through my reader. It wouldn't disappear. 

Ive recently put on a new Battery, it cleared for a while, came back, clears, comes back.

the oxygen sensor cables look to be in good nick. Is it worth changing the sensors out before presuming it's the catalytic converter as I'm lead to believe?

 

thanks in advance 

[daveh_rav4]

Hi, can you post the fault codes that are being displayed?  Someone on here may be able to identify a fault from them. 

If a new Battery cleared the problem for a while you might want to check that the alternator regulator voltage is producing the correct charge voltage... normally about 13.6volts I believe with the engine at about 1000rpm or above (stick a voltmeter across the Battery terminals).  Also check that your Battery connections are not contaminated with grease or loose creating a bad connection/resistance.  Also check that the earth cable is well earthed to the chassis. 

Could of course be a bucket full of other things with all the digital dross and sensors polluting modern cars... but that's where I would start.

[crussell]

7 hours ago, daveh_rav4 said:

Hi, can you post the fault codes that are being displayed?  Someone on here may be able to identify a fault from them. 

If a new battery cleared the problem for a while you might want to check that the alternator regulator voltage is producing the correct charge voltage... normally about 13.6volts I believe with the engine at about 1000rpm or above (stick a voltmeter across the battery terminals).  Also check that your battery connections are not contaminated with grease or loose creating a bad connection/resistance.  Also check that the earth cable is well earthed to the chassis. 

Could of course be a bucket full of other things with all the digital dross and sensors polluting modern cars... but that's where I would start.

Thanks, I'll try that when she gets home with the car tonight. 

P0420 and P0430 are the two codes showing. There was also a zero reading on air to fuel reading (I believe threats what it is) so I've attached a photo of the scan if that helps. 

[daveh_rav4]

Opp's, yup... just noticed you had the codes in your header ^ 

OK, I just googled those codes... and as you previously mention they point to emmision codes aka the catalytic convertor.

Check out this auto techs advice on these codes; he also mentions checking the Battery and grounds (earths) etc...

 

Hope this helps...

[rallychief]

I know this thread is a little old, but i bought a RAV 4-2 2.0 vvti  03 plate on Thurs 1st of Feb, from a dealer in Wales 140 miles from home, with 3 months warranty, about 90 miles into the trip home, EML came on, called RAC , the patrolman hooked it up and brought up P4020 fault, and his diagnostics showed it had been cleared 6 times before, now dealing with the garage, as warranty company wont cover it as pre existing fault, so may end up having to sort myself, if you could let me know where you have got to with yours, it could be very helpful.

 

Cheers Chris 

[FROSTYBALLS]

Regardless of the warranty, you probably have a case under the Consumer Rights Act 2015. See section 'The first six months' of the following - https://www.which.co.uk/consumer-rights/regulation/consumer-rights-act

[rallychief]

Thanks for that FROSTYBALLS  thats really useful, i can certainly prove the fault existed prior to purchase, as shown on RAC diagnostic printout, their were several more on the computer screen, not shown on the print out

Rac print out P4020 fault rav 4.pdf

[rallychief]

Ok just an update, the  EML is now back on, took 250 miles, the dealer has offered us a £350 refund to sort the issue, fit a cat or whatever, this dosen't affect the warranty, it was a cheap ish motor to start with, so happy with that, so now working through the possible causes as per the american guide on u tube as mentioned elsewhere in the thread