Leah66

PO420 & 430 codes read after 3 above warning lights came on yesterday. Today, warning lights on dash disappeared and code reader shows no codes. After I tightened the gas cap last night, the warning lights still showed, as well as the codes. Today, all are gone. Could it have been as simple as a gas cap being tightened?

I will watch for the warning lights to appear again, as I’m extremely concerned. If I accidentally cleared the codes on the code reader (new to using this), how long will it take for the warning lights to re-appear?

2005 Lexus RX330/214,000 miles impeccably maintained by previous owner.

why do I smell gas? Why am I only getting 10 mpg? Just purchased this car.

Also, thumping sound over the smallest of bumps in the road coming from rear drivers side cabin (or underneath car) is driving me mad. Read threads on this, but still don’t have a clue as to what this is?

Any help would be appreciated. Thank you.

iMSQ

https://www.engine-codes.com/p0420_lexus.html
https://www.engine-codes.com/p0430_lexus.html

PS: Do you smell gas in cabin or from exhaust?

Leah66

yes, but not 100% of the time.

Margate330

If the Engine Ecu sees a condition that is critical it will throw a code immediately and will not clear on it's own.
However, some codes are not critical and may take a couple drive cycles to trigger and may clear in a couple drive cycles if the problem is fixed or not detected.

If you have live data on your scanner plz post fuel trims and MAF -> car completely warmed up and at idle(750 rpm-ish), A/C off.

I recommend adressing/posting the thumping sound in another existing thread(best) or make a new thread since this is a completely different issue.

Leah66

Thank you. My scanner doesn’t do this. Where should I go to get this done?

iMSQ

Buy an OBD2 scanner.
for example: