Bought the car at 130k miles, passed CA emissions perfectly. This is the 2.7L V6 RWD model. Good service history with regular oil changes and thermometer change. I've had the ATF fluid and differential fluid flushed as preventive maintenance. I've changed the spark plugs, the air filter, and cleaned the MAF. Oil is Castrol 10w30 high mileage oil with a Motorcraft filter.
At around 133k miles, car would randomly have a vibrating rough idle, CEL. The CEL was P0401 which pointed me to EGR valve. The car also randomly became hard to start at this point without tapping on the gas as I was cranking it. Had to replace a battery at this point although it was on it's way out anyway. What is strange is that this randomly happened sometimes and not always. I would say about 10% of the time it was super hard to start and shook on idle. Once you're going, it's totally fine, no loss of power, average fuel economy but when stopped and idling, it was rough.
I had the EGR valve replaced, problem seemed to go away. Then it started happening again a couple hundred miles later. This time I'm getting P0401 and P0420.
The second code details Catalyst system efficiency below theshold bank 1
Could it be O2 sensors or is there something wrong with the CC?
Right now, it seems to be running fine, I'm running a dose of Gumout HM Regane through it and maybe one more dose on the next tank. What is troubling is that it's random. Most of the time, it works perfectly normal with smooth idle. I hope when it happens again I'm in a position to right away bring it to the mechanic because this problem occurs randomly...
At around 133k miles, car would randomly have a vibrating rough idle, CEL. The CEL was P0401 which pointed me to EGR valve. The car also randomly became hard to start at this point without tapping on the gas as I was cranking it. Had to replace a battery at this point although it was on it's way out anyway. What is strange is that this randomly happened sometimes and not always. I would say about 10% of the time it was super hard to start and shook on idle. Once you're going, it's totally fine, no loss of power, average fuel economy but when stopped and idling, it was rough.
I had the EGR valve replaced, problem seemed to go away. Then it started happening again a couple hundred miles later. This time I'm getting P0401 and P0420.
The second code details Catalyst system efficiency below theshold bank 1
Could it be O2 sensors or is there something wrong with the CC?
Right now, it seems to be running fine, I'm running a dose of Gumout HM Regane through it and maybe one more dose on the next tank. What is troubling is that it's random. Most of the time, it works perfectly normal with smooth idle. I hope when it happens again I'm in a position to right away bring it to the mechanic because this problem occurs randomly...
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