The 2021 Blazer shares its platform with GM's 9-speed automatic transmission, which has been problematic across multiple brands. The 2.0L turbo shows early low-speed pre-ignition (LSPI) issues leading to catastrophic engine damage, while the 3.6L V6 is generally more reliable but not immune to transmission gremlins.
2.0L Turbo Catastrophic Engine Failure (LSPI)
Occasional · high severity
Typical onset: 20,000-60,000 mi
Symptoms: Sudden loss of power with metallic knocking, Check engine light with misfire codes, Oil consumption before failure, Metal shavings in oil during regular changes
Fix: Low-speed pre-ignition destroys pistons and rods. Requires complete engine replacement or short block. 18-24 labor hours for R&R. GM has extended some warranties but many owners pay out of pocket.
Estimated cost: $8,000-12,000
9-Speed Transmission Shudder and Slipping
Common · medium severity
Typical onset: 30,000-80,000 mi
Symptoms: Harsh shifts between 2nd and 3rd gear, Shudder or vibration during light acceleration 25-45 mph, Delayed engagement when shifting to Drive or Reverse, Transmission overheating warnings
Fix: TSBs call for fluid flushes with updated fluid, torque converter replacement, or complete valve body replacement. Flush takes 2 hours, torque converter 8-10 hours, valve body 12-14 hours. Multiple attempts common before resolution.
Estimated cost: $400-4,500
Transmission Oil Cooler Line Leaks
Common · medium severity
Typical onset: 40,000-90,000 mi
Symptoms: Transmission fluid puddles under vehicle, Burnt transmission fluid smell, Low fluid level warnings, Lines corrode at crimp fittings near radiator
Fix: Hard lines corrode where they connect to cooler. Requires replacement of affected lines and fittings. 3-4 labor hours including fluid refill and system check.
Estimated cost: $600-1,200
Transmission Mount Failure
Occasional · low severity
Typical onset: 50,000-100,000 mi
Symptoms: Clunk when shifting from Park to Drive, Excessive vibration at idle in gear, Visible engine movement during acceleration, Rubber mount separation visible on inspection
Symptoms: Reduced engine power warning, Vehicle enters limp mode unexpectedly, Throttle response lag or complete loss, P2138 throttle position sensor correlation codes
Fix: Throttle body or accelerator pedal position sensor fails. Diagnosis 1 hour, throttle body replacement 1.5 hours, pedal assembly 1 hour. May require both components.
Estimated cost: $500-1,400
Fuel Pump Module Failures
Rare · high severity
Typical onset: 60,000-120,000 mi
Symptoms: No-start condition with full tank, Engine stalling during acceleration, Fuel pressure fluctuations, Whining noise from fuel tank area
Fix: In-tank fuel pump module fails. Requires dropping fuel tank or removing rear seat for access depending on configuration. 4-5 labor hours.
Estimated cost: $900-1,600
Owner tips
If buying a 2.0L turbo, insist on oil analysis reports and inspect for metal in oil — walk away from any consumption history
Have transmission fluid condition checked every 30,000 miles; dark/burnt fluid means trouble is brewing
Use Top Tier gasoline in the 2.0L turbo and avoid lugging the engine below 2,000 rpm under heavy throttle to reduce LSPI risk
Extended warranty is highly recommended for used purchases given transmission and 2.0L turbo risks
The 3.6L V6 is the safer bet; avoid the 2.0L turbo unless you have comprehensive warranty coverage and documented oil analysis history showing clean engine internals.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: AGM battery required for start-stop system; Group 48 (H6) standard for 2.0L turbo engine
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Control Modules — 2021 Chevrolet Blazer
Every control module on the 2019-2024 Chevrolet Blazer — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
⚠️ Controls automatic headlamps, DRL, high beam assist. Configuration programming recommended but not always required.
Tire Pressure Monitor Control Module (TPMS)relearn only +0.2 hr▸ programming details
📍 integrated in BCM
🔧 TPMS relearn tool or GDS2
⚠️ TPMS receiver integrated in BCM. Sensor IDs must be relearned after tire rotation or sensor replacement. 315 MHz sensors.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
General Motors, LLC (GM) is recalling certain 2020 Chevrolet Bolt EV and 2021 GMC Canyon and Sierra 1500, 2500 and 3500, Yukon, Yukon XL, Cadillac Escalade and Escalade ESV and Chevrolet Blazer, Camaro, Colorado, Equinox, Silverado 1500, 2500 and 3500, Suburban and Tahoe vehicles. Incorrect bolts may have been used at one or more fastening locations to secure the seat belts to the vehicle. If an incorrect bolt was used, the seat belt may not be properly attached to the vehicle.
Consequence: If a seat belt assembly is not properly attached to the vehicle, the seat belt may not properly restrain an occupant in the event of a crash, increasing the risk of injury.
Remedy: GM will notify owners, and dealers will replace the suspect bolts, free of charge. The recall began January 29, 2021. Owners may contact GMC customer service at 1-800-462-8785, Cadillac customer service at 1-800-458-8006, or Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N202322230.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2021 Chevrolet Blazer 2.0L I4 Turbo and can vary by trim.
🔧 Built by master technician Chris Hackleman · Master Technician · 20+ years.