2018 Mazda CX-9 · symptom sheet
Check engine light or misfire
- 52owner reports
- 68,000median miles
- $7,800median quote
- 0involved a crash
Newest report Sep 15, 2026 · checked Oct 2, 2026
96 of the 128 complaints on this car are about the engine. 52 of those describe misfire. Only overheating is reported more often on this car.
Tick what matches of 52 reports
Misfire 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
These reports start with the check engine light. Many describe the engine running rough or shaking at idle, a P0300-series code, or a catalytic converter code. A worrying number say the light was flashing. Owners often list ignition coils or spark plugs already replaced, and the light coming back afterward.
What got replaced
Few of these reports name the part that was replaced.
Recalls and investigations
2 recalls on the engine cover the 2018 model year. A recall on the same system isn't always the same failure, so read the defect text.
The impeller inside the low-pressure fuel pump may crack and deform, potentially causing the fuel pump to fail.
The wiring harness may disrupt electrical communications and disable the passenger frontal air bag, turn signals, and/or engine starting system.
All 2 recalls on the 2018 Mazda CX-9, with the owner complaints on each recalled system
What owners paid
6 of the 52 reports quote a price. Each dot is one quote. The middle half runs $6,800 to $11,000.
When it happens
The middle half of failures fell between 53,300 and 102,000 miles, from the 25 reports that gave a mileage.
Is this a known problem?
The manufacturer has sent NHTSA 18 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.
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 ...
Some customers may complain about a poor acceleration and rough idling or the CHECK ENGINE light ON with DTC P0301:00, P0302:00, P0303:00, P0304:00.NOTE: Only turbo engines are applicable; non-turbo engines are NOT applicable.
14 more on the 2018 Mazda CX-9 page.
What owners wrote
“coolant leaks at the cylinder head around the exhaust manifold. Caused crack in the head. The Mazda 2.5t engine has this common issue that Mazda knows about. Mazda has a bulletin out but has not issued a recall. Car over heated and I was left stranded. Took car to mechanic who says I need to replace my entire engine.”
Filed Nov 8, 2024
“Engine cylinder head is leaking coolant. This is a known issue by Mazda as they have submitted a TSB on the issue but have yet to submit a recall. The leak causes overheating along with pollution of coolant fluid into the environment. The problem was diagnosed by a Mazda dealership. The leaking occurred before a light came on the dashboard. The light on the dashboard only came on once the engine began overheating.”
Filed Oct 2, 2024
“Engine coolant leaks at cylinder heads I started noticing the problem at around 50000 miles its a small coolant leak but car is almost 6 years old and now 54000 miles”
Filed Mar 8, 2024 · 50,000 miles
“The cylinder head cracked and leaked engine coolant at 72K miles. This is a known design flaw IAW TSB 01-007/22. Vehicle overheated.”
Filed Sep 5, 2023 · 72,000 miles
Should you keep driving it?
This page can't tell you that. 0 of 52 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.
Guide Which lights mean pull over now? Warning lights by color and urgency
Other problems on this car
- Engine overheats or leaks coolant 69 reports