Diagsheet

2021 Ford Bronco · symptom sheet

Engine failure, knocking or rod bearing

  • 34owner reports
  • 6,000median miles
  • 1involved a crash

Newest report Jul 20, 2026 · checked Sep 9, 2026

73 of the 225 complaints on this car are about the engine. 34 of those describe engine failure. Only stalling is reported more often on this car.

Tick what matches of 34 reports

4
2
9
6
1

What got replaced

Owners who name the part that was replaced mention the engine (34 reports).

Recalls and investigations

3 recalls on the engine cover the 2021 model year. A recall on the same system isn't always the same failure, so read the defect text.

26V-468Jul 20, 2026
Engine

Ford Motor Company (Ford) is recalling certain 2021-2026 Bronco and Bronco Raptor vehicles. The engine compartment wiring harness may become damaged and short circuit.

Risk and remedy
Risk: A short circuit in the engine compartment can create heat or spark, increasing the risk of a fire.
Remedy: Dealers will install sheathing over the wiring, free of charge. This is a Phased campaign. Phase 1 will include 2026 Bronco Raptor notified owners on 7/31/2026. Phase 2 will include 2021-2025 Bronco Raptor vehicle will notify owners on or about 8/14/2026. Phase 3 will include 2021-2026 Bronco will notify owners on or about 9/1/2026. Owner notification letters were mailed August 5, 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 26S55. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on July 23, 2026.
25V-685Oct 10, 2025
Equipment:Electrical:Engine Block Heater

Ford Motor Company (Ford) is recalling certain 2016-2019 Lincoln MKC, 2016-2023 Explorer, 2019-2020 Fusion, 2019-2024 Ranger, 2020-2022 Lincoln Corsair, Escape, 2021-2024 Bronco, Bronco Sport, and 2022-2024 Maverick vehicles. The engine block heater may crack and develop a coolant leak, causing it to short circuit when the block heater is plugged in.

Risk and remedy
Risk: An electrical short circuit can increase the risk of a fire.
Remedy: Owners are advised not to plug in their block heater until the vehicle is remedied. Dealers will replace the block heater, free of charge. Owners will also have a alternative option to replace engine block heater element with a threaded blanking plug, and remove the block heater electrical cord. Interim letters, notifying owners of the safety risk, were mailed December 3, 2025. Additional letters will be sent once the final remedy is available, anticipated September 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 25SA4. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on October 15, 2025.
24V-635Aug 23, 2024
Engine And Engine Cooling:Engine:Hard Parts Internal/Mechanical

Ford Motor Company (Ford) is recalling certain 2021-2022 Bronco, F-150, Edge, Explorer, Lincoln Nautilus, and Lincoln Aviator vehicles equipped with either a 2.7L or 3.0L Nano EcoBoost engine. The engine intake valves may break while driving, which can result in engine failure and a loss of drive power.

Risk and remedy
Risk: A loss of drive power increases the risk of a crash.
Remedy: Dealers will perform an engine cycle test and replace the engine as necessary, free of charge. Owner notification letters were mailed July 3, 2025. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 24S55.

NHTSA investigations into the engine on the Bronco

EA23-002opened Sep 29, 2023
Engine · model years 2021 to 2022

Loss of motive power. Closed oct 31, 2024, led to recall 24V-635.

NHTSA summary
On July 22, 2022, the Office of Defects Investigation (ODI) granted a Defect Petition (DP22001) and opened a Preliminary Evaluation (PE22007) to investigate allegations of loss of motive power in model year (MY) 2021 Ford Bronco vehicles equipped with 2.7L EcoBoost engines. Complainants were reporting sudden engine failure while driving resulting in a loss of motive power, often without the ability to restart. During PE22007, the cause of engine failure and loss of motive power in the subject vehicles was determined to be intake valve fracture, and the full scope of vehicles affected by the subject defect was identified as all MY 2021-2022 Ford and Lincoln models equipped with either the 2.7L or 3.0L EcoBoost engines, referred to as the “Nano” engine family. If an intake valve fractures in the subject engines, it may drop into the cylinder and contact the piston, often resulting in catastrophic engine damage. On September 29, 2023, PE22007 was upgraded to an Engineering Analysis (EA23002) to further investigate the subject defect across the full scope of affected vehicles. During EA23002, ODI visited Ford facilities to review technical information related to intake valve fracture in “Nano” engines, coordinated with NHTSA’s Vehicle Research and Testing Center (VRTC), and analyzed updated field data relating the subject defect. Forensic analysis of fractured intake valves demonstrated that the defective components exhibited “grinding burn” or out of specificatio
PE22-007opened Jul 22, 2022
Engine · model years 2021

Loss of motive power due to valve intake failure on ford bronco vehicles.. Closed oct 2, 2023.

NHTSA summary
The Office of Defects Investigation (ODI) received a petition dated March 16, 2022, requesting an investigation regarding allegations of defective intake valves in model year (MY) 2021 Ford Bronco vehicles equipped with the 2.7L Eco-boost (“Nano”) engines. The petitioner alleged these vehicles are experiencing loss of motive power at any highway speeds with no-restart as a result of catastrophic engine failures. To date ODI is aware of 42 submitted Vehicle Owner Questionnaires (VOQ’s) alleging a loss of motive power. On July 22, 2022, ODI opened a Preliminary Evaluation (PE22-007) to investigate allegations of stalling/loss of motive power on the subject vehicles. Upon receiving Ford’s Information Request (IR) response, ODI learned Ford was aware of 110 consumer complaints (including field reports), 125 warranty claims and 136 engine exchanges related to the 2021 Ford Bronco. Ford’s response indicated these failures are across the “Nano” engine family, which includes both the 2.7L and 3.0L EcoBoost engine variants with a total estimated population of 708,837 vehicles. Additionally, ODI became aware that the subject engines contained intake valves that were manufactured out of a specific alloy known as “Silchrome Lite”, which can become excessively hard and brittle if an over-temperature condition occurs during machining of the component. The overly brittle intake valve can fracture at the keeper grove causing the intake valve to freely contact the pi
DP22-001opened May 27, 2022
Engine · model years 2021

Loss of motive power. Closed jul 28, 2022.

NHTSA summary
The Office of Defects Investigation (ODI) received three petitions on March 17, March 18, and March 29, 2022, which requested a defect investigation into an alleged defect of the valves on model year (MY) 2021 Ford Bronco vehicles equipped with the 2.7L Eco-boost engines. The petitioners alleged that MY 2021 Ford Broncos vehicles are experiencing loss of motive power at highway speeds with no-restart due to catastrophic engine failures.On May 27, 2022, ODI opened this Defect Petition to evaluate whether to grant or deny the petition.ODI has identified 26 Vehicle Owners Questionnaires (VOQs) that relate to the alleged defect in the subject vehicles. Based on ODI's review of the applicable materials, including VOQs, NHTSA has decided to grant the petition and open a Preliminary Evaluation (PE22-007) to assess the scope, frequency, and potential safety-related consequences of the alleged defect.Accordingly, this Defect Petition is closed.The ODI complaints cited above can be reviewed at NHTSA.gov under the following ODI numbers:11448171, 11448461, 11450659, 11450702, 11450737, 11450788, 11450871, 11450879, 11451158, 11451503, 11451957, 11452074, 11452692, 11453669, 11453933, 11454098, 11455294, 11456219, 11456713, 11459262,11460124, 11460125, 11461178, 11463199, 11463296, 11464516.
EA93-022opened Jul 30, 1993
Engine And Engine Cooling · model years 1991 to 1992

Idle air spd ctrl vlv malf. Closed aug 31, 1994.

NHTSA summary
There is no summary currently available
PE93-010opened Mar 2, 1993
Engine And Engine Cooling · model years 1991 to 1992

Idle air spd ctrl vlv malf. Closed jul 30, 1993.

NHTSA summary
There is no summary currently available

When it happens

The middle half of failures fell between 2,322 and 6,976 miles, from the 11 reports that gave a mileage.

2822
223
224
125
126

What owners wrote

“2.7 engine failure while accelerating on to a hwy. Loss of acceleration and power. I was unable to get fully off the road. Engine was replaced under warranty only 3,636 miles on car. No warning lights prior to this failure. Once engine failed and started smoking the check engine light came on.”

Filed Mar 24, 2024 · 3,636 miles

“my car went from 50 mph to nothing. lost power. coasted to the side of the road barely avoiding traffic. dark road, sheriff had to sit behind car so I was not rear ended in pitch dark had to be towed to the dealer. one week later dealer uncertain. likely complete engine failure maybe fuel valve less than one year old. 11,000 miles”

Filed Sep 22, 2022 · 11,000 miles

“On May 17th At 6,800 miles my motor randomly experienced catastrophic engine failure and has been at the Ford dealership since. The dealership has not told me anything on how or why this happened other than the motor needs to be replaced. The dealer received the new motor on June 22nd.”

Filed Jul 20, 2022 · 6,800 miles

“Engine completely destroyed with no notice at 4600 miles destroyed itself in less than three minutes while driving. New engine replaced”

Filed Jun 12, 2022 · 4,600 miles

Should you keep driving it?

This page can't tell you that. 1 of 34 reports involved a crash. Owners who file are the ones who had a bad experience, and nobody checks their reports. If the problem affects steering, braking, power or a fire risk, treat it as a safety fault and have it inspected before a long or high-speed drive.

File your own report with NHTSA. Complaint counts are how a problem gets an investigation.

Other problems on this car