2018 Mazda CX-9 · symptom sheet

Engine overheats or leaks coolant

67owner reports
75,000median miles
$7,600median quote
0involved a crash

Newest report Aug 8, 2026 · checked Sep 19, 2026

76 of the 126 complaints on this car are about the engine. 67 of those describe overheating, which makes it the most reported problem on the 2018 CX-9.

Tick what matches of 67 reports

the temperature gauge climbed into the red

coolant is disappearing or on the ground

white smoke from the tailpipe

the heater stopped blowing hot

the dealer found a head gasket or cracked block

the engine was replaced afterward

What got replaced

Owners who name the part that was replaced mention the radiator (4 reports) and the coolant hose or reservoir (3 reports).

Recalls and investigations

No recall on the engine covers the 2018 model year as of Sep 19, 2026.

What owners paid

7 of the 67 reports quote a price. Each dot is one quote. The middle half runs $6,800 to $11,000.

$6,800$7,600$11,000

$0k$2k$4k$6k$8k

When it happens

The middle half of failures fell between 56,000 and 88,080 miles, from the 29 reports that gave a mileage.

822

2723

2324

425

526

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 67 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.