2021 Chevrolet Blazer Problems: 5 Issues Every Owner Should Know
2021 model year · 0+ owner reports · Updated April 2026
According to Au7o's analysis of 0+ owner reports, the 2021 Chevrolet Blazer has 5 documented known issues. No issues are rated critical, indicating generally reliable ownership. Across all issues, repair costs range from $0 to $4,000. DIY maintenance guides at au7o.io.
All 5 Known Issues
On the 2019-2024 Chevrolet Blazer, the 2019+ Blazer with the 9-speed automatic transmission (9T50/9T65) develops a shudder during acceleration from a stop, particularly between 1st and 2nd gear. GM bulletin PIP5608J addresses TCC shudder/surge issues. The root cause involves excess lubrication on internal parts contaminating the transmission fluid. Some owners require torque converter or full transmission replacement.
Common Symptoms
- Shuddering during acceleration from stop
- Hesitation or jerking between 1st and 2nd gear
- Vibration at low speeds (20-40 MPH)
- Rough or delayed shifting
- Bucking sensation during light acceleration
How to Fix
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- UpgradeTransmission flush kit for complete fluid exchange to address shudder (Liqui Moly Transmission Flush Kit)
- UpgradeFull synthetic ATF designed to reduce shudder in automatic transmissions (Valvoline MaxLife ATF Full Synthetic)
On the 2019-2025 Chevrolet Blazer, the Blazer uses the GM 9T50 (2.0T/2.5L FWD) or 9T65 (3.6L AWD) 9-speed automatic with similar shift quality concerns as other GM 9-speed applications. Harsh shifts, delayed engagement, and shudder at light throttle are reported. GM has released multiple TCM calibration updates.
Common Symptoms
- Harsh or clunky shifts
- Shudder at light throttle
- Delayed shift from Park
- Gear hunting on hills
How to Fix
TCM recalibration with latest software. Fluid exchange with Mobil 1 LV ATF HP. Most issues resolve with software updates.
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- TipTSB 20-NA-136 specifically lists 2019 Blazer with 9T65 (RPO M3V) for 1-2 upshift slip/flare and hesitation 5-15 mph. First authorized step is TCM calibration update. If dealer says 'no calibration available', request second opinion - GM has released multiple 9T65 updates since 2019. Print TSB from NHTSA.gov and bring to appointment
- TipIf TCM reprogramming doesn't resolve harsh shifts, next step per TSB 20-NA-136 is valve body and solenoid pack inspection. P0756 (Shift Solenoid B Performance/Stuck Off) is a known 9T65 failure mode not resolvable by software. Solenoid pack is integral to valve body - both replaced together
- NoteIf Blazer experiences complete loss of drive, sudden neutral at highway speed, or recurring hard shifts after TCM updates, escalate to GM Customer Care (1-800-222-1020) and request field engineer review. Extended warranty or goodwill repair granted in documented repeat-failure cases on 9T65. Same transmission as Traverse, Equinox, GMC Terrain
- UpgradeTransmission flush kit for complete fluid exchange to address shudder (Liqui Moly Transmission Flush Kit)
- UpgradeFull synthetic ATF designed to reduce shudder in automatic transmissions (Valvoline MaxLife ATF Full Synthetic)
On the 2019-2025 Chevrolet Blazer, the 9-speed automatic transmission (9T50/9T65) produces a noticeable shudder during light acceleration and torque converter lockup, typically between 30-50 mph. Harsh or delayed shifts, especially 1-2 and 2-3, are also common complaints. GM has issued multiple TSBs addressing transmission calibration.
Common Symptoms
- Shudder during light acceleration at 30-50 mph
- Harsh 1-2 shift
- Delayed downshift
- Transmission hesitation from stop
How to Fix
Start with a transmission fluid flush using the updated Mobil 1 Synthetic LV ATF HP fluid and a TCM reprogramming to the latest calibration. If shudder persists, the torque converter may need replacement. GM has a customer satisfaction program for some VINs — check with your dealer for eligibility.
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- UpgradeTransmission flush kit for complete fluid exchange to address shudder (Liqui Moly Transmission Flush Kit)
- UpgradeFull synthetic ATF designed to reduce shudder in automatic transmissions (Valvoline MaxLife ATF Full Synthetic)
On the 2019-2025 Chevrolet Blazer, the AGM battery required for the auto start-stop system degrades prematurely, often failing within 2-3 years. When the battery weakens, the start-stop system disables itself and various electrical warnings appear. The auxiliary battery (on equipped models) can also fail, compounding the issues.
Common Symptoms
- Start-stop system not functioning
- Battery warning messages
- Multiple warning lights on startup
- Slow cranking
- Electrical accessories resetting
How to Fix
Replace the AGM battery with a genuine ACDelco AGM battery — standard flooded batteries are not compatible with the start-stop system. After replacement, a battery sensor reset via a scan tool is required. Some owners permanently disable start-stop with aftermarket modules if they find the feature annoying.
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- UpgradeHigh-performance AGM battery with excellent cold cranking amps and deep cycle capability (Optima RedTop AGM Battery)
- UpgradeOEM-quality replacement battery with reliable performance (ACDelco Professional AGM Battery)
- UpgradeAutomatic battery maintainer to prevent parasitic drain issues during storage (Battery Tender Junior 12V Battery Charger Maintainer)
- UpgradeOEM-quality replacement sensor for accurate readings and proper system function (Bosch Replacement Sensor)
On the 2019-2022 Chevrolet Blazer, the 2019+ Blazer infotainment system (Chevrolet Infotainment 3) suffers from screen lockups, lag, and unresponsive touch input. The screen can freeze on the backup camera view or refuse button and touch input. GM bulletin PIT5790A acknowledges the issue but initially had no fix available. Bluetooth and Apple CarPlay disconnections are also common. Some owners have had the radio module replaced.
Common Symptoms
- Touchscreen unresponsive or lagging
- Screen freezes on backup camera or other display
- Bluetooth audio disconnects randomly
- Apple CarPlay/Android Auto connectivity issues
- Volume and audio controls unresponsive
How to Fix
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- UpgradeProfessional OBD-II diagnostic scanner for reading infotainment and body module codes (BlueDriver Bluetooth Pro OBD2 Scan Tool)
- UpgradeAutomotive relay replacement set for common relay failures (Bosch Automotive Relay 5-Pin 12V)
- UpgradeDigital multimeter for diagnosing fuse, relay, and module electrical faults (Innova Digital Multimeter)
- UpgradeOEM-quality replacement sensor for accurate readings and proper system function (Bosch Replacement Sensor)