NHTSA Engineering Analysis: Loss of Motive Power in Ford Bronco (EA23-002)

EA23-002 at a glance

What is NHTSA investigating in the Ford Bronco?

From NHTSA’s investigation 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 specification hardness in the area of the keeper grooves.

The presence of grinding burn is evidence that during the groove grinding phase of production, the temperature of the valve became sufficiently high to alter the microstructure of the material and is indicative that the valve supplier's manufacturing processes were not within control specifications.

Grinding burn results in a hard, brittle microstructure and high residual stresses toward the surface of the valve.

Through normal engine loading, a valve with grinding burn will likely fracture at the area of highest vulnerability, which is the third keeper groove.

In its response to the EA23002 Information Request (IR) letter, Ford provided evidence of 396 customer complaints (including field reports), 825 warranty claims, and 936 engine exchanges.

When considering both ODI and manufacturer failure report data, there have been reports representing 1066 unique vehicles within the subject vehicle population.

Analysis of the failure report data demonstrates that vehicles equipped with potentially defective intake valves were built within a production "spike period" of May 2021 – October 2021.

The beginning of the spike period corresponds to a ramp up in production at the valve supplier manufacturing facility, and the end of the spike period aligns with the implementation of several mid-production process improvements and the decision to change the metal alloy used to produce intake valves from "Silchrome Lite" to "Silchrome 1".

Ford began investigating the subject defect in July 2021, determined the root cause, and took corrective measures for the new production vehicles.

Analysis of the failure report data demonstrates that these corrective actions were successful in eliminating the risk of intake valve fracture for subject vehicles produced after October 2021.

However, Ford did not take any field action to address vehicles produced during the spike period, and in the several months following the implementation of the production changes, a significant number of field failures continued to occur.

It is Ford's assessment that not all valves produced during the spike period are defective, and that failures associated with the subject defect occur at low time in service.

Analysis of the failure report data demonstrates that the vast majority of failures have occurred before 20,000 miles with over half of all reported failures occurring before 5,000 miles.

The rate of reported failures related to the subject defect has steadily decreased since November 2021.

ODI coordinated with NHTSA's National Center for Statistics and Analysis (NCSA) to conduct statistical analysis and predict the number of future failures associated with the subject defect.

The results of this analysis, and the trends identified through the failure report data are generally consistent with Ford's assessment that defective intake valves will likely fail at a low time in service and indicate that the majority of subject vehicles equipped with defective valves have already experienced a failure.

On August 23, 2024, Ford submitted recall 24V635 for subject vehicles equipped with "Nano" engines and built within the production spike period identified above (total population 90,736 vehicles).

The remedy includes an inspection at a Ford/Lincoln dealership where the lifetime engine cycles of the vehicle will be determined.

If a vehicle does not meet a threshold for lifetime engine cycles, the dealership will conduct a high RPM engine cycle accumulation procedure, which aims to identify if the vehicle is equipped with defective intake valves.

Any vehicle that fails the accumulation procedure will receive an engine replacement under the recall.

In addition to recall 24V635, Ford has stated that it will launch customer satisfaction campaign 24N12, which will provide extended warranty coverage to the subject vehicles through the earlier of 10 years or 150,000 miles.

In view of the recall action being taken by Ford, ODI is closing this Engineering Analysis.

To review the reports cited in the Closing Resume ODI Report Identification Number document, go to NHTSA.gov.

What is an engineering analysis?

Engineering Analysis is the second, deeper stage of a federal defect investigation, opened when a preliminary evaluation finds enough evidence. NHTSA can test vehicles and demand detailed engineering data, and this stage often ends with a recall or a recall request.

Did this investigation lead to a recall?

Yes. NHTSA lists recall 24V635000 as the result of this investigation: 2021-2022 Ford Bronco Engine Recall (24V635).

Which vehicles are part of this investigation?

What are Ford Bronco owners reporting to NHTSA?

NHTSA’s public database lists 3,273 owner complaints filed since 2020 for the vehicles in this investigation (all components). Complaints are unverified owner reports.

What should owners do?

1. Check your VIN at nhtsa.gov/recalls for any open recall on your vehicle.
2. If you have the problem NHTSA is investigating, take the vehicle to a dealer now and get a repair order, even if the dealer cannot find anything.
3. Keep a log of every time the problem happens: date, mileage and what happened. Photos and videos help.
4. File your own complaint at nhtsa.gov/report-a-safety-problem. Owner complaints are what start and expand investigations.
5. If the problem keeps coming back, talk to a lemon law attorney.

Recalls on the same vehicles

• 2026 Ford F-150 Rear Suspension Recall (26V577)
• 2023-2027 Ford F-150 Fuel Tank Mount Recall (26V578)
• 2026 Ford Explorer Front Air Bag Recall (26V581)
• 2026 Ford Bronco Curtain Air Bag Recall (26V580)
• 2026 Ford F-150 Differential Recall (26V576)
• 2026 Ford Maverick Body Panel Recall (26V550)
• 2026 Ford Explorer Engine Recall (26V548)
• 2026 Ford Explorer Engine Recall (26V532)
• 2021-2023 Ford F-150 Backup Camera Display Recall (26V489)
• 2025-2027 Ford Explorer Seat Power Seat Recall (26V470)

Can a recall or defect investigation make my car a lemon in California?

Not by itself. What matters is whether a covered defect keeps coming back or keeps your vehicle at the dealer, and a federal investigation or recall is strong evidence that the problem is real.

Under California’s Song-Beverly Consumer Warranty Act, a manufacturer that cannot fix a warranty defect that substantially impairs a vehicle’s use, value or safety within a reasonable number of attempts may have to repurchase or replace it (Civ. Code 1793.2(d)). Within the first 18 months or 18,000 miles, the law presumes a reasonable number of attempts after two repairs of a defect likely to cause death or serious injury, four repairs of the same defect, or more than 30 days out of service (Civ. Code 1793.22(b)).

An owner who prevails can recover reasonable attorney fees and costs from the manufacturer (Civ. Code 1794(d)). You pay nothing, win or lose. We are paid only if you win, and the manufacturer pays our fees, including in settlements. If a case is lost, our firm covers the costs.

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