Owners report a cascade of electrical failures that start intermittently and escalate. The most dangerous: Stabilitrak and reduced engine power warnings that trigger full stalls—sometimes at highway speed with 70 mph traffic around them. The vehicle loses steering assist and braking power, forcing coasting to the shoulder. It may restart after minutes or hours, then fail again weeks later. Mechanics throw parts at it (throttle body, accelerator pedal assembly, wheel speed sensors, ABS modules), owners pay hundreds, and the stall recurs within days or months. Diagnostic codes (P2138, P0523, P2135, P0642) point to sensor voltage and 5V reference failures, but nobody nails a permanent cure.
The ignition switch recall (14V355000) issued in August 2014 promised a fix—but dealers had no parts for months. When parts finally arrived, GM's solution was a plastic ring on the key, not replacement of the faulty switch itself. Some owners' keys got trapped in the ignition; the vehicle wouldn't restart; power steering locked up mid-drive.
Rear defrost connectors burn and melt inside the fuse box, destroying the defrost and creating a fire hazard. Headlights flick on and off on their own; radios turn on unprompted; climate controls won't turn off. One vehicle wouldn't even start after the connector burned.
A few owners reported brake failure and steering lock-up during driving, with air bags that failed to deploy. Multiple owners cite research showing hundreds of complaints across 2008–2017 Impalas—same issues, same codes, same lack of answer.
Failure modes owners describe
Stabilitrak/traction control malfunction with reduced engine power and stall
Service Stabilitrak, Service Traction Control, and Reduced Engine Power warning lights illuminate, often accompanied by engine stall and loss of power steering/brakes at highway speeds. Vehicle may restart after minutes of shutdown, or issue may recur intermittently over months. Owners report difficulty diagnosing root cause—multiple mechanics perform different repairs (throttle body, gas pedal, ABS sensors, wheel speed sensors, accelerator pedal position sensor) without lasting fixes. Diagnostic codes cited include P2138 (throttle/pedal position sensor voltage correlation), P0523 (oil pressure sensor), P2135, and P0642 (lost 5-volt reference circuit).
When: 33,000 to 145,000 miles; onset ranges from first month of ownership to intermittently over years
Symptoms owners cite: Check Engine light and Service Stabilitrak light illuminate together; Service Traction Control warning appears; Reduced Engine Power warning displayed; Engine stalls or power loss at all speeds (10–70 mph); Loss of power steering and braking power; Car restarts after several minutes shutdown; Issue intermittent—recurs weeks, months, or years later despite repairs; Cruise control disabled when warning appears; Dashboard gauges fluctuate
Codes mentioned: P2138, P0523, P2135, P0642
Repairs/costs cited: Owners report replacing throttle body, gas pedal, wheel speed sensors, wheel bearings, ABS sensors, accelerator pedal assembly, and various harnesses. One owner cited need for right front hub (13582664), wheel speed sensor harness (10340314), accelerator pedal (84018392), and vent valve (2085252). Repairs are not permanent; issue recurs despite multiple part replacements.
Recalls/TSBs owners mention: GM issued repair notice (mileage coverage up to 120,000 miles) allowing reimbursement for prior repairs; owners above mileage threshold denied coverage. No permanent recall issued for this intermittent stall/power loss condition.
Ignition switch failure—key stuck, stall at speed, loss of power
Ignition switch fails to hold Run position or becomes stuck in Accessory, causing engine shutdown at highway speeds without warning. Key becomes trapped in ignition and cannot be removed. Vehicle loses electrical power, and restarting is inconsistent or impossible. NHTSA Campaign 14V355000 was issued; however, GM's 'fix' consisted of a plastic key ring insert or key head cover—not replacement of the faulty ignition switch itself. Dealers reported parts unavailability for extended periods despite recall notification (August 2014 through months later).
When: 38,000 to 145,000 miles; incidents reported from 2013 onward; recall issued August 2014
Symptoms owners cite: Engine shuts off at all speeds without warning; Key becomes stuck in ignition; cannot be removed; Loss of power steering and braking at highway speed; Ignition switch stuck in Accessory mode; Vehicle will not restart or restarts inconsistently; Instrument panel remains illuminated after shutdown
Repairs/costs cited: Recall 14V355000 specified 15-minute repair using 2 × 16 mm key rings and insert/cover for key slot—not replacement of defective switch. Owners paid for full ignition switch replacement out-of-pocket (costs not cited in narratives). Recall parts were unavailable from dealers for months after recall notice issued.
Recalls/TSBs owners mention: NHTSA Campaign 14V355000 (Electrical System). GM issued repair notice in August–October 2014. Parts unavailable for months; dealers unable to provide estimated availability. GM acknowledged issue but repair limited to key ring modification, not switch replacement. Some owners received reimbursement for prior out-of-pocket repairs if within coverage window.
Rear defrost connector burned/melted—fire hazard
Rear defroster connector in passenger-side fuse box or under carpet melts and burns due to overcurrent, creating fire risk and rendering rear defrost inoperative. Owners discovered burned connector only after rear defrost stopped working; no warning signs reported prior to failure. Connector design inadequate to handle current flowing through fuse.
When: Timing not specified; owners discovered after losing rear defrost function (one owner noted loss after 3 weeks of cold-weather driving)
Symptoms owners cite: Rear defrost stops working; Burned/melted connector discovered under passenger footwell fuse box or under carpet; Charred/blackened connector; wires melted together; Fire hazard—potential for ignition if not caught early
Repairs/costs cited: Owners identified issue via internet videos showing similar burned connectors. Repair entails replacing connector. No cost figures provided in narratives.
Recalls/TSBs owners mention: No manufacturer response mentioned in narratives. Issue appears widespread across multiple Impala model years but no recall issued.
Electrical system intermittent failures—headlights, radio, climate controls
Headlights activate and deactivate independently; radio turns on/off without user input; air conditioning makes abnormal noise and fails intermittently; interior becomes extremely hot whether vehicle on or off. Climate control and interior lights behave erratically. One vehicle failed to start after rear defrost connector burned. Defrost/demist function inconsistent between Air and Defrost modes.
When: 58,000 to 63,000 miles
Symptoms owners cite: Headlights turn on/off independently; Radio activates/deactivates without user command; Air conditioning makes abnormal noise; Interior temperature uncontrollable (stays hot even when AC on or vehicle off); Vehicle fails to start; Climate control fan runs continuously after shutdown; Defrost and Air modes produce same output; Interior lights remain on or dim/brighten erratically
Repairs/costs cited: Dealer diagnostics performed; some reset unknown codes without permanent fix. One vehicle required Auxiliary Motor Power replacement (not completed). No permanent repair outcomes documented.
Recalls/TSBs owners mention: Manufacturer was notified in some cases; no recalls issued. Dealer attempted code resets without success.
Battery failure—stuck key, inaccurate fuel gauge, multiple warning messages
Battery fails, leaving ignition switch stuck in Accessory mode with key unable to release. Fuel gauge reads inaccurately; unknown messages display on dashboard in different languages (possible corrupted data display). Vehicle loses electrical power.
When: 68,000 miles
Symptoms owners cite: Ignition switch stuck in Accessory mode; Key cannot be removed from ignition; Inaccurate fuel gauge reading; Unknown messages in different languages displayed; Total loss of electrical power
Repairs/costs cited: Dealer diagnosed battery failure but did not repair vehicle.
Recalls/TSBs owners mention: Manufacturer not contacted. Battery failure attributed as cause, though context suggests electrical system design issue.
Brake failure during traffic maneuver—no stopping power
Brake pedal depressed but vehicle failed to stop during approach to stop sign, resulting in crash into curb and embankment. Vehicle included in NHTSA Campaign 14V355000 (Electrical System), suggesting electrical failure caused brake loss. Air bags failed to deploy.
When: Failure details not provided; vehicle registered in recall 14V355000 (2014)
Symptoms owners cite: Brake pedal depressed but no stopping power; Crash into curb and embankment; Air bags failed to deploy
Repairs/costs cited: Vehicle not diagnosed or repaired.
Recalls/TSBs owners mention: NHTSA Campaign 14V355000 (Electrical System) covered this VIN; suggests electrical root cause, though no explicit recall for brake failure issued.
Traction control malfunction causing loss of control and stall at highway speed
While driving at highway speed (70 mph), traction control light illuminates and vehicle stalls. Loss of steering control during motion causes crash. Air bags fail to deploy on impact.
When: 56,000 miles
Symptoms owners cite: Traction Control light illuminates; Vehicle stalls at 70 mph; Loss of steering control; Crash occurs; Air bags fail to deploy
Repairs/costs cited: Vehicle not diagnosed or repaired.
Recalls/TSBs owners mention: NHTSA Campaign 14V355000 (Electrical System) applied to this VIN.
Steering wheel lock-up at highway speed
At 70 mph, Check Engine light, Service Stability Track, Engine Reduced Power, and Service Throttle warnings illuminate. Vehicle loses all RPMs and steering wheel almost fully locks while still in motion, creating extreme loss-of-control hazard.
When: Specific mileage not provided
Symptoms owners cite: Check Engine light; Service Stability Track warning; Engine Reduced Power warning; Service Throttle warning; Loss of all RPMs; Steering wheel nearly locked while moving at 70 mph
Repairs/costs cited: Owner barely veered off road to safety; no repair details provided.
Recalls/TSBs owners mention: None mentioned.
Accelerator pedal malfunction—hesitation, grinding at takeoff
Vehicle grinds and hesitates when taking off from stop, backing out of driveway, or during acceleration. Symptoms occur unpredictably and do not reproduce during mechanic inspection. Turning Traction Control off eliminates grinding and hesitation temporarily, but issue returns each time vehicle is restarted. Affects multiple model years (2007, 2011, 2013) within same owner fleet.
When: Occurs at takeoff, backup, or any acceleration; recurring with each engine start
Symptoms owners cite: Grinding noise during takeoff from light; Hesitation/lurch when accelerating from stop; Lunge-like sensation as if unable to shift into first gear; Symptoms disappear during mechanic inspection; Turning Traction Control 'OFF' temporarily stops issue; Problem recurs with each restart
Repairs/costs cited: No permanent repair identified. Workaround: disable Traction Control before each drive (must be repeated every time vehicle started).
Recalls/TSBs owners mention: No recall or service bulletin mentioned.
Synthesized from 80 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.