2021 Mercedes-Benz C 300

Problems, Recalls & Reliability Report

Excellent Reliability

Quick Summary

The 2021 Mercedes-Benz C 300 has 15 owner complaints filed with NHTSA — that's 0.2x the segment average of 80. The most common issue is engine problems (47% of all complaints), specifically: piston connecting rod broke and left the engine making holes in both sides of the block; mercedes benz rejected any responsibility because the car has a branded title. currently a new engine (brand new) is being installed, my concern is that what will happen if the new engine has the same defective .

Total Complaints

Recalls Issued

—/5

Safety Stars

0.2x

vs Segment Avg

Known Problems

ENGINE

7 complaints

47%

• Piston Connecting Rod broke and left the engine making holes in both sides of the block; Mercedes Benz rejected any responsibility because the car has a branded title. Currently a new engine (brand new) is being installed, my concern is that what will happen if the new engine has the same defective
• First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/
• the check Engine light fault code P012D12 The pressure sensor upstream of the turbocharger had a short circuit to positive. Found Kink wire on upstream pressure sensor. A short circuit to positive. Electrical Wire replaced.

Typical onset: 50K miles Est. repair: $500

“Piston Connecting Rod broke and left the engine making holes in both sides of the block; Mercedes Benz rejected any responsibility because the car has a branded title. Currently a new engine (brand new) is being installed, my concern is that what will happen if the new engine has the same defective ”

— NHTSA complaint filing

FUEL SYSTEM

3 complaints

20%

• While driving car on Sunday 10/5, it suddenly failed to respond to gas pedal pressure. The car stopped accelerating and rather slowed to 15 MPH, almost causing a car from behind to hit me in the rear side.
• My car had a coolant leak last year a hose broke and I have a 2021. My son’s mercedes sis the same thing on 11/23/2025. I have researched ma y others with this same issue. There should be a recall on that hose or whatever the problem Is.
• The contact owns a 2021 Mercedes Benz C. The contact stated that while driving on the highway, the vehicle began to lose power, riding rough. The check engine light illuminated. The vehicle was towed to the dealer where it was diagnosed with a fuel injection failure. The vehicle read diagnostic

Typical onset: 50K miles Est. repair: $500

“While driving car on Sunday 10/5, it suddenly failed to respond to gas pedal pressure. The car stopped accelerating and rather slowed to 15 MPH, almost causing a car from behind to hit me in the rear side.”

— NHTSA complaint filing

AIR BAGS

1 complaints

• The contact owns a 2021 Mercedes-Benz C300. The contact stated while driving at an unknown speed, there was a burning odor inside the vehicle. The contact stated the passenger side air bags was enabled warning light was illuminated. The contact also stated the vehicle made an abnormal noise. The con

Typical onset: 50K miles Est. repair: $500

“The contact owns a 2021 Mercedes-Benz C300. The contact stated while driving at an unknown speed, there was a burning odor inside the vehicle. The contact stated the passenger side air bags was enabled warning light was illuminated. The contact also stated the vehicle made an abnormal noise. The con”

— NHTSA complaint filing

ELECTRICAL

1 complaints

• First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/

Typical onset: 50K miles Est. repair: $500

“First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/”

— NHTSA complaint filing

DRIVER ASSIST/CAMERAS

1 complaints

• Rearview camera not displaying any image when transmission is put in reverse.

Typical onset: 50K miles Est. repair: $500

“Rearview camera not displaying any image when transmission is put in reverse.”

— NHTSA complaint filing

Estimated Repair Costs

ENGINE(~50K mi)

$500

FUEL SYSTEM(~50K mi)

$500

AIR BAGS(~50K mi)

$500

ELECTRICAL(~50K mi)

$500

DRIVER ASSIST/CAMERAS(~50K mi)

$500

Estimates based on average reported repair costs. Actual costs vary by location, shop, and severity.

🔍 Pre-Purchase Inspection Checklist

Based on 15 owner complaints for this specific year, here's what to check or ask about:

☐
ENGINE: Piston Connecting Rod broke and left the engine making holes in both sides of the block; Mercedes Benz rejected any responsibility because the car has a branded title. Currently a new engine (brand new) is being installed, my concern is that what will happen if the new engine has the same defective
Typically appears around 50K miles. Repair cost ~$500
☐
FUEL SYSTEM: While driving car on Sunday 10/5, it suddenly failed to respond to gas pedal pressure. The car stopped accelerating and rather slowed to 15 MPH, almost causing a car from behind to hit me in the rear side.
Typically appears around 50K miles. Repair cost ~$500
☐
AIR BAGS: The contact owns a 2021 Mercedes-Benz C300. The contact stated while driving at an unknown speed, there was a burning odor inside the vehicle. The contact stated the passenger side air bags was enabled warning light was illuminated. The contact also stated the vehicle made an abnormal noise. The con
Typically appears around 50K miles. Repair cost ~$500
☐
ELECTRICAL: First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/
Typically appears around 50K miles. Repair cost ~$500
☐
General: Get a pre-purchase inspection from an independent mechanic ($100-$200)