The 2009 Chevrolet Cobalt electrical complaint cluster exposes systemic design and quality issues spanning ignition, fuel, sensors, and body controls.
Ignition failures dominate this cluster. Dozens of owners report the ignition key stuck in the ON position, refusing to turn off or be removed from the cylinder. The engine continues running after parking. Some owners had to disconnect batteries or pull fuses while engines ran—a dangerous emergency measure—to shut the car down. Dealers replaced ignition cylinders; GM issued Service Bulletin #10256 in late 2010 and later recall campaigns (14V171000, 14E021000), but many affected VINs were excluded despite identical symptoms. Several owners report the recall was completed with defective or used parts, causing the same failure within weeks.
Engine stalls without warning at city and highway speeds (25–65 mph), causing loss of power steering and crashes in at least two cases. These are intermittent, recur over months despite repair attempts, and dealers could not diagnose root causes.
Airbags failed to deploy in two collision events (one head-on at 50 mph, one side-impact at 35 mph), resulting in occupant injuries. Dealers offered no diagnostic data.
Fuel system problems range from corroded and leaking fuel lines (rust occurring where protective tape ends) to fuel pump module connections burning out inside the tank—a fire hazard the service technician explicitly warned about. Strong gasoline odors persist; one owner had a 0.5-inch fuel leak near the muffler.
Throttle body sensors fail, triggering reduced engine power and violent shaking; one owner replaced the entire throttle body, ECM, accelerator pedal assembly with sensor, crankshaft and camshaft sensors, spark plugs, and wires without fixing the P2135 code. Power windows fail on multiple doors; climate controls and wipers activate on their own or stop working. One owner's radio switches to AUX mode spontaneously, repeatedly, while parked or driving.
An EMF meter reading revealed high electrical radiation under the driver's seat where the wiring harness is located—potential exposure concern owners flagged. Battery vent tubing appears factory-installed with improper sizing, allowing hydrogen gas to vent into the passenger cabin instead of outside the vehicle. Door locks engage and disengage by themselves without input.
Failure modes owners describe
Ignition switch stuck in ON position; key won't turn or remove
Ignition key becomes stuck and immovable in the ON or RUN position, preventing the engine from shutting off. The key cannot be removed from the cylinder. Owners report the car continues to run after being parked. Some had to disconnect the battery or pull fuses while the engine ran to stop it—a dangerous practice. Dealers identified the ignition cylinder as faulty and replaced it.
When: Between 3 and 70,000 miles; often early in ownership or without warning
Symptoms owners cite: Key will not turn from RUN to OFF position; Key stuck in ignition and cannot be removed; Engine continues running after parking; May require jiggling key or steering wheel to attempt reset; Occasional intermittent sticking before complete failure
Repairs/costs cited: Ignition cylinder replacement; some owners cited steering column replacement needed. Costs reported between $106–$797 including labor. GM Service Bulletin #10256 (issued Dec 2010) addressed the issue but many VINs were excluded from recall coverage despite identical symptoms.
Recalls/TSBs owners mention: Recall #10256 (Ignition Cylinder), NHTSA Campaign 14V171000 (Electrical System), NHTSA Campaign 14E021000 (Electrical System: Ignition Switch). Parts shortages delayed recall repairs by months. Some owners reported recall was completed with defective or used parts, causing the same failure to recur within weeks or months after repair.
Engine stalls unexpectedly during driving
Engine shuts off while driving at highway or city speeds (25–65 mph) without warning. Owners could restart the vehicle after waiting several minutes or removing and reinserting the key. Multiple stalls reported on the same vehicle over weeks or months. Loss of power steering occurred in at least one incident, causing a crash.
When: Various mileages; 4,100 to 119,000 miles; incidents recur intermittently
Symptoms owners cite: Complete loss of engine power while driving; No warning lights or symptoms before failure; Vehicle restarts after waiting or key removal/reinsertion; Loss of power steering coinciding with stall; Repeated failures over months despite repair attempts
Repairs/costs cited: One owner had ignition lock cylinder replaced; failure persisted. Another had ECM/TRANS fuse replaced temporarily; issue recurred. No permanent repairs documented in narratives.
Recalls/TSBs owners mention: NHTSA Campaign 14E021000 (Electrical System: Ignition Switch) and Campaign 14E210000 cited. At least one owner's VIN was not included in applicable campaigns despite matching symptoms.
Airbag non-deployment in collision
In head-on collision with a deer at 50 mph, front passenger-side airbags did not deploy despite significant impact damage (broken headlight, crushed hood/grille). In another incident, both front and side curtain airbags failed to deploy after a 35 mph side-impact collision, with occupant injury.
When: At time of collision; vehicles had 33,000 and 41,000 miles respectively
Symptoms owners cite: Airbag did not deploy despite impact forces consistent with deployment thresholds; Airbag warning light appeared intermittently after collision; In one case, airbag module was under warranty but dealership did not diagnose root cause
Repairs/costs cited: Dealers offered no explanation and provided no diagnostic results in narratives. One owner was told airbags 'do that sometimes.'
Recalls/TSBs owners mention: No manufacturer response documented. Owners report service light reset by dealer without addressing underlying issue.
Reduced engine power / power loss with P2135 code
Engine enters reduced-power mode; accelerator pedal loses responsiveness or power is cut. Severe engine shaking and violent vibration. Occurs intermittently or repeatedly. One owner replaced throttle body, ECM, accelerator pedal assembly, multiple sensors, spark plugs, and wires without resolving the issue.
When: 119,000 miles reported in one case; recurs despite multiple part replacements
Symptoms owners cite: Reduced engine power warning light illuminates; No power to gas pedal; Engine shakes violently; Loss of power to drive normally; Code P2135 logged
Codes mentioned: P2135
Repairs/costs cited: Throttle body replacement (~$575 cited), ECM replacement, accelerator pedal assembly replacement with new sensor, crankshaft positioning sensor, camshaft sensor, spark plugs, and spark plug wires. Despite all replacements, problem recurred repeatedly.
Recalls/TSBs owners mention: None documented. No recall identified for this failure.
Ignition switch electrical failures (anti-theft, shift solenoid, starting issues)
Anti-theft indicator illuminates unexpectedly and vehicle fails to start. One vehicle's diagnosis was initially listed as ignition switch, then changed to shift solenoid by mechanic; issue recurred after solenoid replacement. Another vehicle had anti-theft lock turn on by itself after ignition recall repair, preventing normal starting.
When: At various mileages; 160,000 miles and lower; can occur after recall repair
Symptoms owners cite: Anti-theft indicator light on, vehicle will not start; Shift solenoid failure initially diagnosed, then recategorized as electrical issue; Anti-theft lock activates spontaneously after ignition repair; Engine fails to start on subsequent attempts
Repairs/costs cited: Ignition switch replacement attempted; shift solenoid replaced ($300+). Owner reported mechanic indicated broader electrical problem. Second repair pending parts availability.
Recalls/TSBs owners mention: Manufacturer stated VIN not included in recalls; owner declined repair under these terms.
Throttle body / accelerator pedal sensor faults
Throttle body sensor fails after short ownership period. Engine service power detector light comes on, accompanied by shaking. Dealer diagnosed faulty throttle body sensor requiring full throttle body replacement.
When: 3 weeks after purchase; approximately 80,000 miles total on vehicle
Symptoms owners cite: Engine shaking; Engine service power detector light illuminates; Oil and traction service lights on; Loss of engine power
Repairs/costs cited: Throttle body replacement cost $575; was not covered under powertrain warranty as it is classified as electrical rather than powertrain.
Recalls/TSBs owners mention: Dealership advised electrical failures are not covered under powertrain warranty.
Fuel system issues: leaks, module failures, burning odors
Fuel leaks from corroded or damaged fuel lines; fuel pump spewing fuel; strong gasoline odor permeating cabin. Fuel line rust occurs at the point where metal protective tape ends, suggesting moisture trap. Leak is located close to muffler, creating fire risk. Fuel pump module harness connection burned out and fused itself inside fuel tank, creating severe fire hazard.
When: 9 years into ownership (rust-related); 48,000 and 80,000 miles for pump/module failures
Symptoms owners cite: Strong persistent gasoline smell in vehicle; Fuel dripping from undercarriage; Fuel pump spewing fuel over engine; Trouble starting (requires two key turns due to fuel leak); Fuel line rust at metal tape termination point; Burned/melted module harness connection inside fuel tank
Repairs/costs cited: Fuel pump and sending unit replacement required (~$575–$600 range inferred). Fuel tank seal replacement, fuel line replacement, or section repair needed. Corroded fuel lines prevented recall repairs from being completed. Service technician warned melted electrical connection inside fuel tank was 'very unsafe situation' with fire risk if fuel level had been low.
Recalls/TSBs owners mention: NHTSA Campaigns 12V459000 and 09V419000 cited as fuel system recalls, but owners' vehicles were not included despite identical symptoms. Campaign 14V047000 repair could not be performed due to corroded fuel lines.
Radio switches to AUX mode spontaneously
Radio input switches from FM/AM to AUX mode on its own, unprompted, even while parked or during remote-start operation. Issue worsens over time, occurring repeatedly and consistently.
When: Months 1–2 into observation; happens every time vehicle is used
Symptoms owners cite: Radio audio cuts out mid-listening; Display shows AUX input selected; Occurs while parked, driving, on highway; Happens after remote start: vehicle in AUX mode when owner approaches; No physical switch movement or bumping involved
Repairs/costs cited: None documented; owner disabled radio as workaround.
Recalls/TSBs owners mention: None documented.
Electrical shorts, power window, and climate control failures
Intermittent electrical shorts throughout vehicle. Power windows fail on multiple doors (3 non-working windows in one case). Climate controls (air conditioner and heater) fail to work. Windshield wiper pump activates and dispenses water on its own; burning odor and smoke from AC vents follow. AC/heater control panel goes bad.
When: 25,000–96,000 miles; 59,000 miles for window issues
Symptoms owners cite: Intermittent electrical shorts; Power windows inoperative on passenger doors and rear; AC and heater controls unresponsive; Windshield wipers pump fluid and activate without input; Burning smell and smoke from AC vents; AC/heater control module failure; Unable to start vehicle on several occasions
Repairs/costs cited: Fuel pump and sending unit replacement attempted but did not resolve electrical issues. AC/heater control panel replacement required. Window repairs not completed within warranty period.
Recalls/TSBs owners mention: Vehicle not included in NHTSA Campaign 12V459000 (Fuel System), though fuel-related electrical issues present.
Keypad door locks malfunction after ignition recall repair
After ignition switch recall service, keypad for remote door locks stops functioning. Doors cannot be locked/unlocked via keypad.
When: Shortly after recall repair service; 28,000 miles
Symptoms owners cite: Keypad buttons for door locks no longer responsive; Cannot lock or unlock doors remotely
Repairs/costs cited: Micro switch replacement needed; repair not completed.
Recalls/TSBs owners mention: Repair performed as part of ignition recall (new ignition keys installed), but introduced new electrical failure.
Burning rubber odor from steering wheel area
Strong burning rubber smell originates from steering wheel area, occurring after ignition recall repair.
When: Shortly after recall repair service; 28,000 miles
Symptoms owners cite: Burning rubber odor from steering column/wheel area; Occasional difficulty removing ignition key without positioning steering wheel in specific orientation
Repairs/costs cited: Root cause not identified; related to electrical/steering column assembly.
Recalls/TSBs owners mention: Ignition recall service completed but did not resolve or prevent this secondary failure.
Power steering overheating and lockup during parking maneuvers
Power steering suddenly locks up and becomes impossible to turn during parking practice (parallel parking and 3-point turns). Dealer acknowledged this is a known problem with a GM service bulletin because the computer-controlled power steering can overheat during extended low-speed maneuvers, but stated nothing can be fixed.
When: During driver training; vehicle under 100,000 miles likely
Symptoms owners cite: Steering wheel becomes immovable; Occurs during slow-speed parking maneuvers; No warning before lockup
Repairs/costs cited: Dealer advised no fix available despite known issue.
Recalls/TSBs owners mention: GM issued service bulletin acknowledging power steering computer overheat issue during prolonged low-speed steering; no remedy provided.
Brake light stays illuminated at all times; BCM calibration/replacement needed
Brake light indicator remains on continuously and functions only intermittently. Requires BCM (Body Control Module) recalibration or replacement. Issue recurs after repair.
When: 25,000–59,000 miles; multiple visits to dealer
Symptoms owners cite: Brake light illuminated at all times; Brake light functions intermittently; Failure recurs after BCM recalibration attempt
Repairs/costs cited: BCM recalibration attempted; failure persisted. Later diagnosis recommended BCM replacement.
Recalls/TSBs owners mention: None documented.
Odometer digital display malfunction / inaccurate mileage reading
Digital odometer displays inaccurate mileage. Owner reports tire shop indicated 12,000 miles since last tire purchase three months prior, yet odometer showed only ~4,000 miles gained. Owner suspects manufacturer is under-reporting mileage to avoid warranty obligations.
When: Early in ownership (59,740 miles at complaint with 7+ years ownership)
Symptoms owners cite: Digital odometer reading inconsistent with tire wear and service records; Tire shop independently verified 12,000 miles in 3-month period; Odometer shows much lower mileage accumulation
Repairs/costs cited: Dealership tested odometer; stated no problems found despite owner's evidence.
Recalls/TSBs owners mention: Dealership denied malfunction; no further investigation.
Electrical wiring harness excessive radiation / EMF emission under driver seat
Wiring harness located too close to driver and passenger seats under driver-side seat. EMF meter reading showed high electrical radiation levels when vehicle powered on, exceeding safe limits. Radiation readings spiked within 12 inches of wiring harness area where driver and passenger would sit. Complaint suggests electromagnetic shielding deficiency.
When: Present from new; identified via EMF testing
Symptoms owners cite: High EMF radiation detected on meter; Wires located in immediate seating area; Radiation spike when vehicle powered on
Repairs/costs cited: None; no manufacturer response or remedy identified.
Recalls/TSBs owners mention: None documented; complaint suggests recall and EMF shielding needed.
Battery vent tube misfit; hydrogen gas venting into cabin
Battery vent tube (plastic tubing connected to battery elbow valve) appears to have an inner diameter too small for the male nipple fitting, causing the tube to split where it attaches. This allows vented hydrogen gas to escape into the trunk, which opens to the passenger compartment, creating a fire and explosion hazard.
When: Present from factory at time of complaint; vehicle age not specified but design/installation issue
Symptoms owners cite: Plastic vent tube split at connection point to battery; Hydrogen gas venting into trunk/passenger area instead of outside vehicle; Potential fire/explosion risk from hydrogen accumulation
Repairs/costs cited: No repair documented; owner offered to provide photographic evidence.
Recalls/TSBs owners mention: None documented; complaint flags potential factory defect across multiple models using similar vent tubing.
Headlight marker cover separation; glare hazard
Front headlight side marker covers came off on both headlamps at different times. Covers did not fall off due to impact or accident but separated on their own.
When: After several years of ownership; both sides eventually affected
Symptoms owners cite: Marker cover separates from headlight housing on both sides; Causes glare and visibility issues
Repairs/costs cited: None documented.
Recalls/TSBs owners mention: GM informed owner that 2009 model-year headlights are not recalled, though same issue exists on 2005 models which were recalled.
Door lock buttons malfunction; locks engage/disengage on their own
Power lock buttons do not function reliably. Locks will engage and disengage by themselves multiple times without any driver input, whether the car is being driven or parked.
When: Multiple incidents over time period
Symptoms owners cite: Power lock buttons unresponsive; Locks cycle on and off spontaneously; Multiple lock/unlock cycles with no driver action; Occurs while driving and while parked
Repairs/costs cited: None documented; owner states gear shifter buttons sometimes work as alternative.
Recalls/TSBs owners mention: None documented.
Synthesized from 123 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.