Owners consistently describe fuel odors ranging from faint to overpowering, detected both inside the cabin and externally. The root issues center on fuel system leaks at the pump module and fuel lines. The most commonly cited failure is a cracked plastic port on the fuel pump's modular reservoir or a crack in the fuel pump housing itself, causing fuel to leak from the top of the tank or onto the protective shield underneath the vehicle. Fuel line corrosion also appears, especially in designs where lines sit in a pocket above the muffler, trapping heat and moisture. Mechanics have found cracked fuel return lines, damaged fuel supply lines, and corrosion at fuel line connections.
Fuel leaks typically occur between 30,000 and 200,000 miles, though some are reported as early as 2,700 miles. Owners report fuel pooling underneath the vehicle, sometimes near the exhaust system—a fire hazard concern mentioned repeatedly. Some vehicles also exhibit difficulty starting, check engine lights, and stalling. Fuel economy has degraded in several cases.
A frustration running through the narratives is coverage gaps: owners note that 2006–2007 Cobalts were recalled under campaign 09V419000 and 12V459000, yet many 2008 models with identical symptoms were not included despite having the same components and failure modes. Repairs performed outside recalls have cost owners $200 to $750 per incident, with some corrosion issues recurring within two years.
Failure modes owners describe
Cracked fuel pump housing/module
The plastic supply port or housing of the fuel pump modular reservoir cracks, allowing fuel to leak from the top of the fuel tank or pump assembly onto the protective shield below the vehicle.
When: 30,000 to 200,000 miles; one reported at 2,731 miles
Symptoms owners cite: Strong fuel odor inside and outside the vehicle; Fuel leaking from underneath the vehicle; Fuel pooling on protective shield under tank
Codes mentioned: P2270
Repairs/costs cited: Fuel pump module or pump assembly replacement; costs reported at $200 to $750; one case cited module kit cost of $745.12
Recalls/TSBs owners mention: NHTSA Campaign 12V459000 (fuel pump), NHTSA Campaign 09V419000 (2006–2007 model coverage); many 2008 VINs excluded from recalls despite identical symptoms; some dealers denied coverage citing flood damage history or mileage over 120,000; Louisiana-registered vehicles initially excluded from campaign coverage
Cracked fuel lines and return lines
Fuel supply lines, return lines, or fuel line assemblies crack and leak fuel. Some lines show corrosion due to design placement in a pocket above the muffler, trapping heat and moisture.
When: 32,000 to 175,000 miles; corrosion recurring after 2 years in one case
Symptoms owners cite: Fuel odor while driving and when parked; Visible fuel leaking from rear driver-side wheel well or underneath vehicle; Fuel leaking onto the exhaust system; Degraded fuel economy; Difficulty starting
Repairs/costs cited: Fuel line replacement; one case replaced entire fuel line and fuel pump assembly as one unit; costs cited at $200 to $750; corrosion issues requiring replacement again after 2 years
Recalls/TSBs owners mention: NHTSA Campaign 12V459000; most lines not covered by recall; one GM representative confirmed design flaw (muffler placement causing heat/moisture trap) but declined responsibility; dealer refused to honor warranty due to flood damage history
Fuel pump connector burn/ignition risk
Fuel pump electrical connectors overheat and burn, creating a fire hazard during vehicle operation.
When: Unspecified mileage; associated with difficulty starting
Symptoms owners cite: Difficulty starting the vehicle; Burned fuel pump connectors visible to mechanic; Risk of ignition during driving
Repairs/costs cited: Connector repair or replacement (not detailed); multiple owners expressed fear of fire but repair status not clearly stated in narratives
Recalls/TSBs owners mention: GM issued recalls for 2007–2009 Cobalts with this problem; 2008 model owner's vehicle was excluded from recall despite identical failure
Fuel delivery system malfunction with check engine light
Fuel system fails to deliver fuel properly, accompanied by engine warning lights and intermittent stalling.
When: 2,731 miles (very early failure); at least one case at 187,000 miles
Symptoms owners cite: Check engine warning light illuminated; Abnormal fuel odor while driving; Vehicle stalling at various speeds; Difficulty starting after short parking periods
Codes mentioned: P2270
Repairs/costs cited: Root cause not determined in one early case; fuel pump assembly leaking in another case
Recalls/TSBs owners mention: Dealer and manufacturer notified in some cases; no assistance provided in narratives reviewed
Synthesized from 43 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.