QuestionThanks for your help in advance 1998 tacoma 4cyl 5 speed
I have 3 trouble codes brought up witn a scan tool
po401 EGR flow insufficien
po420 catalyst efficiency below threshold (bank 1)
po420pd same as above
do I need to replace the cat converter? 800.00 at dealer!!!
Two trouble codes for the cat?
truck has 316000 miles, runs good except gas mileage suffers
Could you please tell me what I need to do
Many thanks again!!!
AnswerThe two codes are not related and are seperate issues, the po401 is an EGR trouble code, in most cases, about 90% of the time it is due to a bad EGR modulator valve, it's attached to the EGR valve, it's the round plastic thing with three vacuum hoses on it, try replacing it and see if it helps, if not then I would recommend also replacing the egr vacuum switching valve(VSV) located under the intake chamber, replacing both almost always fixes the po401 code. Cat converter problems are not uncommon on these engines and a po420 normally means the cat has to be replaced, consider having an independent muffler shop replace it with an aftermarket converter for less than half the cost of the dealer item.
