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Got an old, free Lexus that runs great… But throws a CEL about 5 minutes after clearing it…
The car has 165k miles, but has an great running engine and transmission, so I want to fix it to be my beater car.
Yesterday the left turn signal blinked fast, (still not fixed… Think it is the front bulb), the clock, power mirrors, and cigarette lighter didn’t’ work either… Ended up replacing a fuse and ALL 3 of those systems now work. I Los replaced a handful of missing plastic clips/nylon rivets being the last monkeys that replaced bulbs never bothered to put the plastic trim back!
I also cleaned the MAF sensor with CRC Mass Air Cleaner, but I could NOT remove those rusted screws, so I took the whole snorkel off to clean it.
Today it is getting new Stabillus hood struts, air the tires, check tire wear, possibly rotate, change that front left turn signal and wipers.
There is also some hose that goes to the air box! which is missing a clamp… Will fix that. While in there it will get a new air filter being this on is BAD BAD BAD.
That said I still need to scan it again, I suspect both codes to have returned. Obviously at least one code did to set the CEL.
What do I replace next? Obviously P0420 is a CAT, but it could be set in error due to a bad O2 sensor etc.
From what I can tell P0171 is a lean condition, possibly fuel filter, pump, or pressure regulator, or injectors, but the engine runs smoothly, and bank 2 isn’t impacted with a code, so this doesn’t make much sense.
Some notes say vacuum leak or bad PCV valve. I have no idea how to test for vacuum leaks… But replacing the PCV would be simple and inexpensive.
Other indications are possibly a bad O2 sensor or IACV…
Simply put, how does one know which part(s) to replace?
If there is more than one problem, the second should be easier to diagnose once the first is resolved… In theory.
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Replies
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P0171:
Likely vacuum leak at manifold gasket for that bank:Viewing fuel trim data will also help you diagnose.
P0420:
Yep, cat likely toast, how to verify:
http://ericthecarguy.com/faq/solving-automotive-performance-issues?start=8#CatalyticConverterProblems
Think those IR thermometers are around $28 now at harbor freight with coupon($35 normally).
http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465-8905.html?ccdenc=eyJjb2RlIjoiNDI2MDU2NTEiLCJza3UiOiI2OTQ2NSIsImlzIjoiMjcuOTkiLCJwcm9kdWN0X2lkIjoiODkwNSJ9#.UzSJc4U0flo
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