Code P300 on a car I am thinking of buying

2006 CHEVROLET COBALT

155,000 MILES • 0.6L • 4 CYL • 2WD • AUTOMATIC

KAMBEN

MEMBER
1 POST

Question, so i am looking at the car listed above that is throwing p300 code. Spark plugs, oil change, fuel injectors and new exhaust system done. It putters and shuts off when you stop. Starts fine.
Looked online and there's so much it could be. But i am without a car, got kids and just looking for something to get me through until March or April.
Ideas?

Jul 18, 2019 at 9:43 AM

ASEMASTER6371

✓ASE Certified Mechanic
52,796 POSTS

Good afternoon,

I would start with a compression test to be sure the motor is good.

https://www.2carpros.com/articles/how-to-test-engine-compression

The most common issue for the 300 code is low fuel pressure. I would have the fuel pressure tested to be sure it is not a fuel pump.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

A mass air flow sensor could also cause this but it would code if it was reading wrong values.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Roy

P0300
Descriptor
Probable Causes
Crankcase Ventilation System Vacuum Leak
Diagnose Other DTCs First
Exhaust System Restricted
Fuel Contaminated
Powertrain Control Module (PCM) Grounds and Connections Loose or Corroded
Spark Plug Worn, Fouled, Cracked or Incorrectly Gapped
Vacuum Hoses and Seals Split, Restricted or Connected Incorrectly

Jul 18, 2019 at 10:19 AM

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