NHTSA Engineering Analysis: No Restart After Auto Start/stop Engages in Acura MDX (EA25-004)

EA25-004 at a glance

What is NHTSA investigating in the Acura MDX?

From NHTSA’s investigation summary:

On June 3, 2022, the Office of Defects Investigation (ODI) opened Preliminary Evaluation PE22005 after the agency received VOQs and several field reports concerning the Auto Idle Stop (AIS) feature on 2016-2019MY Honda Pilot vehicles.

The complaints allege that the engine fails to restart on its own from a complete stop at a traffic light or road intersection with the AIS function engaged.

The subject vehicles are equipped with a 3.5L engine with a 9-speed automatic transmission.

On January 6, 2023, Honda released service bulletins 23-008 and 23-009.

These service bulletins address the failure to restart issue in the 2016-2019MY Honda Pilot vehicles, as well as the 2015-2020 Acura TLX, 2016-2020 Acura MDX, 2019-2022 Honda Passport, and 2020-2023 Honda Ridgeline vehicles.

The repair outlined in the service bulletins is a two-stage countermeasure to remedy the issue.

The first stage is a Programmed Fuel Injection ("PGM-FI") software update.

The second stage is only deployed if the software update fails to remedy the issue.

The second stage, depending on the model and model year, consists of replacement of the starter assembly, starter relays, and a valve adjustment.

Additionally, Honda extended the warranty coverage to 10 years with unlimited mileage for vehicles requiring the second stage component replacement.

ODI continues to receive complaints of the AIS failure to restart, with many complainants alleging the campaign countermeasures had been completed.NHTSA has reviewed Honda's Information Request Letter responses involving warranty claims, lawsuits, and consumer complaints in addition to ODI's own data.

This Engineering Analysis is being opened to further consider the potential safety defect, including gathering additional data regarding Honda's service campaign efficacy.

ODI is additionally expanding the scope to encompass all vehicles addressed in Honda's service bulletins 23-008 and 23-009 as well as newer model year vehicles, which are substantially similar to the vehicles covered by the service campaign.

To review the ODI reports cited in the Opening 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?

Not yet. The investigation is still open, and NHTSA has not listed a recall from it. Investigations can take months. If your vehicle already has the problem, document every dealer visit now.

Which vehicles are part of this investigation?

What are Acura MDX owners reporting to NHTSA?

NHTSA’s public database lists 3,171 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 Honda Pilot Rear Suspension Recall (26V424)
• 2021-2022 Honda Pilot Rear Suspension Recall (26V365)
• 2021, 2023 Acura TLX Passenger Air Bag Recall (26V332)
• 2021-2022 Honda Odyssey Air Bag Control Module Software Recall (26V227)
• 2023 Honda Accord Seat Fastener Recall (26V054)
• 2021-2026 Honda Odyssey Latch and Anchor Recall (25V877)
• 2021-2025 Acura TLX Brake Pedal Recall (25V391)
• 2025 Honda Pilot Rear Seat Belt Recall (25V056)
• 2025 Acura MDX Video Screen Recall (25V032)
• 2023-2025 Honda Pilot Electrical Software Recall (25V031)

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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