This preliminary informational (PI) bulletin provides information to dealership personnel that may be helpful when addressing underbody component corrosion with customers.
full bulletin at NHTSA ↗2018 Chevrolet Impala powertrain problems
moderate Owners of the 2018 Chevrolet Impala have filed 11 NHTSA complaints about the powertrain at roughly $2,500 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See powertrain across all vehicles →
Complaints
11
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2014 Impala | 36 |
| 2015 Impala | 14 |
| 2016 Impala | 15 |
| 2017 Impala | 12 |
| 2018 Impala (this page) | 11 |
| 2019 Impala | 4 |
When does it fail?
Of the 11 powertrain complaints filed for the 2018 Chevrolet Impala, here's the actual mileage breakdown — failures cluster heaviest at 50,000-75,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Powertrain accounts for 19% of all owner complaints filed against this vehicle, across 6 categories tracked.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2.
full bulletin at NHTSA ↗This service bulletin provides information on the harmful effects of ethylene glycol in transmission fluid.
full bulletin at NHTSA ↗This informational bulletin explains Unscheduled Supplemental Services and the importance of GM Simplified Maintenance Schedules.
full bulletin at NHTSA ↗This service bulletin informs the technician of an alternate lift procedure that has been developed when the lift plate does not fit the top of the transmission case for 6T30, 6T35, 6T40, 6T45, and 6T50 Transmissions.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners of the 2018 Chevrolet Impala describe a pattern of transmission problems appearing across the fleet, often before 100,000 miles. The most consistent complaint involves erratic shifting behavior: gears skipping, shuddering during shifts (especially between 2nd and 4th), hard or delayed engagement into 2nd gear, and loss of power during acceleration. Several owners report the transmission suddenly reverting to park without input, then shifting back to the selected gear, sometimes multiple times in succession—on one occasion dropping speed from 65 to 40 mph on a highway. One owner lost all engine power on the highway with the StabiliTrak, ABS, and check engine lights illuminating simultaneously. Hesitation and jerking under throttle input are common, along with complete refusal to accelerate in some instances. Check engine lights appear in some reports but not others. Dealers have diagnosed transmission failure even on vehicles under 100,000 miles with full maintenance records. Repair costs cited include transmission replacement at $6,200. One dealer initially misdiagnosed the issue as engine mounts. Some owners report paying for shifter repairs that did not resolve the underlying problem. The failures happen without warning and at various speeds, both city and highway driving.
Same Chevrolet Impala powertrain reports on nearby years: 2015 · 2016 · 2017
Failure modes owners describe
Transmission shift erraticism and unintended park engagement
Transmission rapidly shifts to park without driver input, then returns to previously selected gear (D/M), often in rapid succession (3-5+ times). Can occur while driving or idling.
When: Varies; occurs at highway speeds (65 mph), on hills, at stop signs, and during merging. No specific mileage pattern noted.
Symptoms owners cite: Sudden shift to park; Rapid cycling back to selected gear; Speed drop (e.g., 65 mph to 40 mph); Loss of acceleration capability; No dash warning lights in some cases
Codes mentioned:
Repairs/costs cited: Dealer unable to identify issue on inspection. Transmission or speed sensor suspected by owner.
Transmission gear skipping and shuddering
Transmission skips gears or shudders violently during gear changes, most commonly between 2nd and 4th gear. Vehicle shudders when shifting.
When: Under 100,000 miles; one case documented with under 100k, another with full dealer maintenance history
Symptoms owners cite: Gear skipping at 1st and 2nd; Shuddering during gear transitions; Shuddering between 2nd and 4th; Jerking and hesitation under acceleration
Codes mentioned:
Repairs/costs cited: Transmission replacement recommended and performed in at least one case ($6,200 cost cited). One dealer initially misdiagnosed as engine mount issue before identifying transmission failure.
Hard or delayed shift into 2nd gear
Transmission hesitates or shifts hard into 2nd gear, with bucking and rough engagement. May occur after full transmission replacement.
When: Intermittent; occurs at low speeds, in stop-and-go traffic, and at highway speeds
Symptoms owners cite: Hard shift into 2nd gear; Bucking and rough shifting; Hesitation under throttle; Jerking during acceleration
Codes mentioned:
Repairs/costs cited: One owner reports hard shifting into 2nd gear persisting even after paying $6,200 for transmission replacement.
Loss of acceleration/transmission failure
Transmission fails to accelerate when pedal is depressed. Vehicle becomes unresponsive, creating hazard at speeds like 45 mph.
When: At 98,000 miles in one documented case; 128,000 miles in another
Symptoms owners cite: Accelerator pedal unresponsive; Vehicle fails to accelerate; Transmission failure diagnosed; Check engine light illuminated (in some cases)
Codes mentioned:
Repairs/costs cited: Independent mechanic and dealer diagnosed transmission failure. Vehicle unrepaired at report time.
Recalls/TSBs owners mention: Manufacturer notified; referred owner to NHTSA Hotline
Stuck in gear with hard acceleration
Vehicle gets stuck in a single gear, making acceleration difficult or impossible. Occurs unpredictably with safety implications.
When: Various times without warning; two instances reported as near-accident situations
Symptoms owners cite: Vehicle stuck in gear; Hard to accelerate; Unpredictable onset; Potential safety hazard
Codes mentioned:
Repairs/costs cited: Shifter repairs attempted but did not resolve issue. Diagnostic cost noted as $1,500+ per dealer estimate.
Complete engine power loss with stability control illumination
Vehicle loses all engine power while driving, with simultaneous illumination of StabiliTrak, ABS, and check engine lights. Steering and brakes become stiff and difficult to control.
When: While driving from work and again on highway after leaving work
Symptoms owners cite: Complete loss of engine power; StabiliTrak light illuminated; ABS light illuminated; Check engine light illuminated; ACTION REQUIRED message on LCD screen; Stiff brakes and steering wheel; Loss of vehicle control; Power restored after 10 minutes
Codes mentioned:
Transmission slipping and rough shifting
Transmission slips between gears and exhibits rough or delayed shifts. Occurs both at low speeds and highway speeds.
When: Intermittent; occurs in stop-and-go traffic and while passing at highway speeds
Symptoms owners cite: Transmission slipping; Rough shifting; Bucking back and forth; Intermittent nature
Codes mentioned:
Abnormal transmission noise with hesitation and reverse acceleration failure
Abnormal humming sound accompanies transmission hesitation and jerking. Vehicle fails to accelerate in reverse even with pedal fully depressed.
When: At approximately 128,000 miles
Symptoms owners cite: Abnormal humming from transmission; Hesitation and jerking at various speeds; Reverse gear fails to accelerate; Check engine light illuminated
Codes mentioned:
Repairs/costs cited: Diagnosed as transmission failure by independent mechanic. Vehicle unrepaired at report time.
Recalls/TSBs owners mention: Manufacturer notified; referred owner to NHTSA Hotline
Synthesized from 11 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
I was sold a used car w/ undisclosed accidents. Had many issues within first few weeks. Had transmission cooler lines replaced after they burst. Radiator, compressor, condenser, and much more. Then the Airbag light came on. Dealership said connectors were bad. Fixed it. Light came on again.took it in to dealership. They had it for over two weeks. The GM for all the dealerships Told me the…
Gears skipping and shruddering between 2nd and 4th gear. Chevrolet dealership recommended engine mounts replaces which was a false diagnose. After further inspection and diagnosing, they revealed that my transmission needs to be replaced for 6200$. I paid the 6200$ and now transmission shifting hard into 2nd gear.
Since vehicle purchase in 2018 there is a shifting problem with the transmission. I have paid for shifter repairs and still the problem exist. While driving the car gets stuck in gear and hard to accelerate. The issue happens at various times without warning. There has been two instances that could have led to potential accidents. Upon spraking with and researching other impala owners, this is a…
Had powertrain trouble with your 2018 Chevrolet Impala?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2018 Chevrolet Impala?
It's a documented issue but not catastrophic. 11 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Based on the 11 complaints filed, powertrain issues most often appear around 83,825 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2018/Chevrolet/Impala.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.