How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 2377
Experience:  GM Grand Master Technician 2007. 14 years experience.
Type Your Pontiac Question Here...
GM Tech (Cam) is online now
A new question is answered every 9 seconds

My car is throwing cel p0300 p0301 p0302 p0303 p0304 and

Customer Question

my car is throwing cel p0300 p0301 p0302 p0303 p0304 and p0171
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Pontiac. The Pontiac Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: car idles pretty rough but other then that seems to be running fine ocational stall but on the accelerator and on highway it is fine
JA: Are you hoping to fix this yourself?
Customer: I'm trying to pass emission yes
JA: Is there anything else important you think the Pontiac Mechanic should know about your Pontiac?

JA: What else should I tell the Pontiac Mechanic?
Customer: i have checked all spark plugs
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Pontiac Mechanic about your situation and then connect you two.
Customer: replaced gasket on intake manifold
Submitted: 1 year ago.
Category: Pontiac
Customer: replied 1 year ago.
the car was recently in the shop for a transmission rebuild and repair
the car did not have any of the cel codes before it went in.
Expert:  Roy Belding replied 1 year ago.

good afternoon my name is ***** ***** I will assist

what motor do you have?


Customer: replied 1 year ago.
Customer: replied 1 year ago.
Expert:  Roy Belding replied 1 year ago.

ok, thanks. the one thing that all the codes have in common is low fuel pressure. it is a common reason for the 300 code and all the individual cylinder miss fire codes. the 174 is a lean code which also supports not enough fuel. you need to have the fuel pressure checked to see the actual pressure versus what is needed. you may have a weak fuel pump.


Customer: replied 1 year ago.
i think it could be the pcv valve as well. it will throw a p0171 code for that as well
Expert:  Roy Belding replied 1 year ago.

not miss fire codes. yes it could be but I doubt it


Customer: replied 1 year ago.
well two things can cause a misfire air and fuel. and pcv could have a leak causing a vacuum leak and uncalculated air entering the motor. as well. I'm just also thinking of things this guys had to take apart to replace transmission. its rare for a fuel pump to slowly go out. usually they work or the don't.
Expert:  Roy Belding replied 1 year ago.

why do you think it is related to the repair???

I would start by checking the fuel pressure. that will tell us a lot. once again, a vacuum leak is not the issue here unless your engine idle is abnormally high which you have not indicated