2018 Mazda CX-9 · symptom sheet
Engine overheats or leaks coolant
- 69owner reports
- 76,000median miles
- $9,800median quote
- 0involved a crash
Newest report Sep 17, 2026 · checked Oct 2, 2026
78 of the 128 complaints on this car are about the engine. 69 of those describe overheating, which makes it the most reported problem on the 2018 CX-9.
Tick what matches of 69 reports
Overheating on other CX-9 years
Report counts are for each model year on its own, so a newer car has had less time to collect them.
What this problem usually is
Most owners in this group notice the coolant before they notice the heat: a reservoir that keeps dropping, a sweet smell, or a bright puddle under the front of the car. Across the vehicles on this site, about four in five of these complaints mention coolant, a leak or a puddle, and roughly two in five mention the temperature gauge or overheating.
What got replaced
Owners who name the part that was replaced mention the radiator (5 reports) and the coolant hose or reservoir (3 reports).
Recalls and investigations
No recall on the engine covers the 2018 model year as of Oct 2, 2026.
What owners paid
8 of the 69 reports quote a price. Each dot is one quote. The middle half runs $7,200 to $11,000.
When it happens
The middle half of failures fell between 56,000 and 106,000 miles, from the 31 reports that gave a mileage.
Is this a known problem?
The manufacturer has sent NHTSA 7 service bulletins or notices for the 2018 Mazda CX-9 that deal with this problem. Newest first.
Federal rules make a manufacturer send NHTSA a copy of any notice about a defect that goes to more than one dealer or owner. Most of these are service bulletins, the repair instructions manufacturers send to dealers. NHTSA generally leaves safety recall bulletins out of this file, and recalls are listed separately.
This Service Alert supersedes the previously issued SA(s) and TSB(s) listed below: The changes are noted in Red. SA-035/24 05/31/24 DESCRIPTION There is a concern that some water pumps are being replaced that are not faulty, due to signs of a very small ...
Mazda Motor Corporation has decided to conduct a Customer Service Program (CSP11) to extend the limited powertrain warranty to 10 years or 120,000 miles, whichever occurs first, for necessary repairs if the covered vehicle has coolant leaks at the cylinder ...
Some vehicles may have coolant leaks at the cylinder head around the exhaust manifold (as shown below). There may be cracks at the stud bolt hole (1) or at the outside of the exhaust manifold flange (2) on the cylinder head.
CSP11 - COOLANT LEAKS AT CYLINDER HEAD WARRANTY EXTENSION For certain 2019-2020MY CX-5, 2016-2020MY CX-9, 2018-2020MY Mazda6 that are equipped with SKYACTIV-G 2.5T engine, the warranty coverage for specific repair of the coolant leak at cylinder head is extended to: 10 years (120 months) or 120,000 miles (192,000 ...
3 more on the 2018 Mazda CX-9 page.
What owners wrote
“Engine coolant leaking due to cracked cylinder head, found by Mazda dealership service inspection and diagnostics. Powertrain warranty only covers this until 80,000 miles, our vehicle is 116,000.”
Filed Dec 21, 2023 · 80,000 miles
“We noticed a coolant leak and took vehicle in for service. Told that engine has a Coolant Leak at Cylinder Head [XXX] . 5 year old vehicle, 56k miles. No other warnings. All maintenance has been previously performed as required. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)”
Filed Oct 21, 2023 · 56,000 miles
“Car started idling rough and losing power at 135000 miles. Then started to overheat. Mechanic noticed coolant was low and added some. Problem continued to get worse and now engine wonât turn over. Mechanic said it was a cracked head leaking coolant into engine and itâs a known problem with the CX-9.”
Filed Sep 22, 2023 · 135,000 miles
“Just noticed coolant leak during oil change. Vehicle has 77,000 miles. Power train warranty is only to 60K. The vehicle is undriveable without major engine work or engine replacement.”
Filed Sep 18, 2023 · 77,000 miles
Should you keep driving it?
This page can't tell you that. 0 of 69 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. How reports land on this sheet.
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Other problems on this car
- Check engine light or misfire 52 reports