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Dan, Technician
Category: Pontiac
Satisfied Customers: 23473
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Pontiac Bonneville SSEi: My check engine light is on and the

Resolved Question:

My check engine light is on and the code is 404 and 420. The 404 suggests it is a bad egr valve or sensor. I was told that it wasnt bad and my fuel pump was replaced along with the fuel filter and the throttle was cleaned. The engine light is still on and it still dies and sometimes hard to start. Do you think it would be the egr valve?
Submitted: 4 years ago.
Category: Pontiac
Expert:  Dan replied 4 years ago.
Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks. P0404 usually means egr valve has failed..I would remove and inspect to see if it is sticking open...If egr is good then problem is PCM or wiring between pcm adn egr..P0420 usually means the catalhytic converter has failed. Let me know if you have questions, thanks.
Customer: replied 4 years ago.
What is pcm? Would a bad egr also cause the 420?
Expert:  Dan replied 4 years ago.
PCM is Powertrain Control Module which is the main engine computer...EGR could cause P0420 but not likely...So I would still fix the egr related code before worrying about the P0420 code. Let me know if you have questions, thanks.
Customer: replied 4 years ago.
I'll back up a lil bit. First the chk engine light read bad catalytic converter 6 mos ago. I had that changed and 3 mos ago the light came back on with these 2 codes. I took it back and they cleared the code and said all was fine. Meanwhile the light came back on and my car began dying while driving and hard to start at times. Then they changed the fuel pump,filter etc..Still having the same problem along with the rpm's going to 0 and the car sputtering when they do this. I took it back again and now they say it is the ignition module. I was wondering if I should change the egr valve 1st as I cant afford to keep putting $ and the problem not going away.
Expert:  Dan replied 4 years ago.
Converter usually doesnt allow engine to go over a certain rpm...egr will make it run rough at lower rpm's...Sounds more like a egr problem. Let me know if you have questions, thanks.
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