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Matt J
Matt J, Chevy Technician
Category: Chevy
Satisfied Customers: 1399
Experience:  10+ years automotive tech, 5 years of experience in a GM dealer
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2003 chevy suburban: v8..The check engine light is on - idles..rough

Customer Question

I have a 2003 chevy suburban. It is a v8. The check engine light is on - idles very rough. Computer codes came back as P0174 and P0300. What do I need to do first.
Submitted: 8 years ago.
Category: Chevy
Expert:  Matt J replied 8 years ago.

Hello my name is XXXXX XXXXX I will be more than happy to assist you.


The top possiblities are:

Tune up - plugs and wires

Low fuel pressure - Fuel pump going out, clogged injectors, or fuel pressure regular

Vacuum Leak at intake manifold gasket .


Far as where to start will depend on what tools you have.


Do you have a fuel pressure gauge and/or a can of starter fluid

Customer: replied 8 years ago.
I have a can of starter fluid
Customer: replied 8 years ago.
something I forgot to tell you. When going up hill or sometimes when excelerating the check engine light flashes on and off.
Expert:  Matt J replied 8 years ago.
Flashes once or Flashes a lot
Customer: replied 8 years ago.
flashes 10-15 times before returning to solid on.
Customer: replied 8 years ago.
Also, we thought we got a bad tank of gasoline because the problem occurred very close to the time we filled up. We put a "gas dryer" in and ran the tank out, then filled up again and put a fuel injector cleaner in, but same symptoms.
Customer: replied 8 years ago.
The same symptoms, but not sure if same computer codes, occurred in December of 2007. The shop that fixed it replaced "Bank 2 Side 1 Oxygen Sensor 43" and replaced the "Intake gasket based upon a service bulitin".
Expert:  Matt J replied 8 years ago.

I will have to thing on this one,


The only time the check engine light will flash is when raw fuel is being dumped in to the exhaust.


The only problem is your vehicle is setting P0174 which is a lean fuel code. Which means your truck is not getting enough fuel.


First thing I would do is swap Bank 1 Sensor 1 Oxygen Sensor and Bank 2 Sensor 1 Oxygen Sensor and see if the problem check engine light keeps the same code of changes. See pic below for location.






Matt J and 2 other Chevy Specialists are ready to help you
Customer: replied 8 years ago.
I cannot swap these tonight, but after doing so tomorrow can I contact you again thru this same link???
Expert:  Matt J replied 8 years ago.

Yes just let me know tomorrow. make sure you clear the codes out, Then dive it until the light comes back on.