American Honda Motor Co., Inc. (AHM) is searching for certain 2016-2020 MDXs, RLXs & TLXs with a client complaint of the Malfunction Indicator Light (MIL) on with the DTC P030X (Cylinder Misfire Detected), P0171 & P0174 (Rear/Front Bank Fuel System Too Lean), or P219A&B (Air-Fuel Ratio Variation of Cylinder) stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to you attempting a repair of any kind.
full bulletin at NHTSA ↗2018 Acura RLX engine problems
moderate Owners of the 2018 Acura RLX have filed 3 NHTSA complaints about the engine at roughly $3,100 to repair (U.S. federal records, as of August 2026). Source: NHTSA Office of Defects Investigation. See engine across all vehicles →
Complaints
3
Recalls
0
Avg fix
$3,100
| Model year | engine complaints |
|---|---|
| 2014 RLX | 3 |
| 2018 RLX (this page) | 3 |
When does it fail?
Of the 3 engine complaints filed for the 2018 Acura RLX, here's the actual mileage breakdown — failures cluster heaviest at 75,000-100,000 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.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine 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.
Service Bulletin - The timing belt area chirps after the engine warms up.
full bulletin at NHTSA ↗Service Bulletin - The timing belt area makes a chirping noise after the engine warms up.
full bulletin at NHTSA ↗Service bulletin - The high pressure fuel pump area chirps after the engine is warm. The high pressure fuel pump is making a chirp noise. NOTE: This noise does not impact the pump, engine function, or reliability.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
What owners are reporting 3 most recent
My vehicle has the same 3.5 liter naturally aspirated V6 that comes in the Acrua MDX which is currently on recall for connecting rod bearings on vehicles with 3.5-liter V6 engines can fail, leading to complete engine failure. my car has the excact same engin with the exact same problem. i have the full diagnosis and estimate from Acura ENGINE REPLACEMENT
The first time I heard the engine noise was on [XXX]. I brought the vehicle to the Schaumburg Muller Acura dealership and dropped it off on May 20. On May 21, the dealership performed an initial inspection and informed me that they needed authorization to further disassemble the engine in order to determine the cause of the problem. I provided that authorization, and by May 22 the engine had been…
The contact owns a 2018 Acura RLX. The contact stated while driving 30 MPH, the oil change and tire rotation messages were displayed. The contact stated that a dealer was contacted. The contact stated that an oil change and tire rotation were performed, and the contact was informed that the engine was knocking. The contact received a call notification from the dealer two days after the vehicle…
Had engine trouble with your 2018 Acura RLX?
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 engine problem on the 2018 Acura RLX?
It's a documented issue but not catastrophic. 3 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 3 complaints filed, engine issues most often appear around 92,000 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 $3,100 for engine 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 engine?
No active recalls currently cover engine 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/Acura/RLX.
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.