2019 Mazda CX-9: engine overheating

Filed Nov 6, 2026 · Engine · MS

We recently noticed a coolant smell upon cold start up of our 2019 Mazda CX-9 Signature. Upon further investigation, we found that there is a Service Bulletin (TSB-01-013/21) issued by Mazda for a manufacturer's defect in the cylinder head causing coolant leaks into and around the exhaust manifold. This is a known and widespread issue, but our car's warranty has lapsed due to mileage (187K miles).

Filed Jul 10, 2026 · Engine, Transmission · KY

The engine cylinder head developed an internal coolant leak, allowing coolant to enter the combustion chamber. This caused engine overheating and smoke coming from the tailpipe while driving. A dealer performed a coolant pressure test confirming coolant leaking into the combustion chamber, and wet/dry compression testing on all 4 cylinders showed low and inconsistent readings consistent with cylinder head coolant intrusion (Cylinder 1: 105/125 psi, Cylinder 2: 115/125 psi, Cylinder 3: 110/175 psi, Cylinder 4: 160/190 psi). Overheating creates a risk of sudden loss of power and potential engine failure while driving, including on the highway. The problem has been confirmed and diagnosed by an authorized dealer service center, and the manufacturer's technical hotline department reviewed the diagnostic findings directly. Warning symptoms (overheating codes and visible tailpipe smoke) first appeared at the time the vehicle was brought in for diagnosis. The manufacturer has an active technical service bulletin addressing cylinder head coolant leaks on this engine and model, along with a related warranty extension program, but has denied coverage for this repair on the basis that the leak is internal rather than external.

Filed Jan 31, 2026 · Engine · CA

- Coolant leak at cylinder head and turbo at only 63,000 miles. - Safety issue because no warning lamps or messages appeared and potential for car to overheat without coolant circulating in the system. Car could breakdown at worst time and location. Leaking coolant onto exhaust created potential for fire. - Problem has not been confirmed by dealer yet. Appointment is upcoming. - Symptoms of the problem were leaking coolant on ground, low coolant level, heater not working properly. - First appeared 1/29/2026.

Filed Sep 30, 2025 · Engine · FL

1. What component or system failed or malfunctioned, and is it available for inspection upon request? ANSWER: Engine failure due to overheating. 2. safety & indicators: ANSWER: During evening rush hour traffic on a 3 lane highway my car went into a form of engine power saving mode while i had children in the vehicle; this was almost catastrophic form my family and the other vehicles around me. there was NO warning. there were no previous issues with my vehicle, this was unexpected. 3. technician review: this is a known issue with no warning: The technician inspected your vehicle and found a concerning issue with the engine overheating. They scanned the vehicle and found a trouble code P111A, indicating the engine coolant reached a temperature of 251.6 degrees Fahrenheit, forcing the engine into limp mode. Based on their experience, the technician believes the engine likely reached much higher temperatures, potentially causing internal damage to the engine block. After a thorough inspection, they found no external coolant leaks, but upon using a digital borescope, they discovered evidence of coolant entering and being burned off in Cylinder 3. Given the severity of the issue, the technician recommends replacing the entire engine to ensure the long-term reliability and extended life of your vehicle. Services completed: - Scanned vehicle and found trouble code P111A - Inspected engine and found no external coolant leaks - Used digital borescope to inspect cylinders and found coolant entering Cylinder 3 Recommendations: - Replace the entire engine

Filed Mar 28, 2025 · Engine, Suspension · CO

Failed water pump, blown head gasket, major coolant leak, and warped head causing the vehicle to overheat and die when coming to a stop. Vehicle died when stopped in construction on a highway and we were nearly rear-ended. Vehicle never showed check engine light and temperature gauge never showed that vehicle was overheating but significant damage was caused to the engine from “excessive temperatures.” Failure of warning signals allowed us to continue driving the car with a significant engine issue. Now the entire engine needs replaced at only 83,000 miles. Car was diagnosed by licensed independent repair shop. Additionally, front struts went out at approximately 40,000 miles making the car wobble at higher speeds. Was inspected and replaced by dealership.

Filed Feb 27, 2025 · Engine · NC

Car coolant warning light came on for a short time 5 min after starting car, then would go off. During severely cold days it would come on then go off once the car was warm. On 2/25/25 the coolant warning light appeared and stayed on. The car made loud rickety noise, as it warmed up. After driving 2 miles the car coolant light turned red and began blinking. An alert appeared saying car over heating. The car was stopped and smoke came out of the car. The car leaked blue/greenish fluid. Overnight the car cooled. The next day the car continued making loud rickety noise driving to dealership. Dealership would not honor extended warranty for coolant leaks at the cylinder. The water pump cracked, with coolant leak also causing the cylinder to crack and leak oil. Dealership is suggesting total engine replacement. The car has gone through its normal servicing with no reported issues of coolant leak or depletion. The engine overheated in a span of 2 miles after being parked for 8 hours. The car was

Filed Oct 16, 2024 · Transmission · NJ

2019 CX-9 GT, 30K miles, in August found coolant leaking under the car. This was 5 months past the warranty (but only 30K miles!). After doing research online, I found this is a massively common issue with all engines from several years encompassing 2019, where the coolant leaks due to a cracked cylinder head. There is a TSB from Mazda, which requires replacement of the engine, once the crack is developed. I immediately called Mazda corporate on 8/15/2024 and opened the case with them. They said they can try to assist, but first I have to take the car to the dealer for diagnosis of the problem. Had to wait 2 weeks, then leave the car, they did a full inspection and confirmed cracked cylinder head. Dealer opened up claim with Mazda (which apparently is separate from the case I made when I called the corporate). I had to go back because Mazda warranty dept. was asking the dealer to prove the engine was overheating, which it hasn't yet, because I kept adding coolant, so the engine never overheated. But the dealer lowered the coolant and had the engine overheat a little bit just to generate the computer code the warranty dept was requiring. This itself was an unnecessary additional potentially damaging scenario, completely unnecessary when the crack in the cylinder head was already found, and the coolant leak is clearly present. After all this, Mazda lowered their original quote from $10K to $6K and expect me to pay this to replace the engine. I called the corporate (customer relations) many times, but they said if the warranty dept. decided this, they cannot change it. And there's no way to talk to warranty dept. directly (not customer facing). We purchased a brand new factory assembled car for well over $40K. Due to a very common, Mazda acknowledged, engine manufacturing defect, the major component of the vehicle, its engine, requires replacement at only 30K miles! This is NOT a reasonable expectancy when purchasing any vehicle.

Filed Jun 29, 2024 · Engine · CA

I have a coolant leak that I have not been able to locate. Despite replacing the radiator, the leak persists. When I contacted the dealer to inquire about estimates for changing the water pump and timing chain, they advised that it would be more cost-effective to replace the entire engine, which would require removing the existing engine at a starting cost of $5,000, with a new engine costing approximately $6,000. They suggested that if I'm already experiencing issues, it might be better to either replace the engine or consider selling the vehicle and purchasing a new one. This response implies that the dealer might be aware of a larger underlying issue and prefers not to address it directly. Experiencing a coolant leak while on the freeway can lead to serious consequences. It can cause the engine to overheat, potentially resulting in significant engine damage and a complete breakdown. This not only poses a safety risk to the driver and passengers but also to other motorists due to the possibility of losing control of the vehicle.

Filed Jun 13, 2024 · Engine · VA

2019 Mazda CX-9 Coolant Leak. 1st warning light just discovered on June 10, 2024. Dealership quoted not under warranty and will cost $14,000 to replace engine. Mazda has an open TSB Technical Service Bulletin for this and many other Mazda's with the same engine- TSB-Coolant Leaks at Cylinder Heads, Bulletin # - 01-013/21 issued 10/15/21 (CRACKED CYLINDER HEADS). Need Mazda to stand by their product and remedy impacted owners.

Filed Jun 6, 2024 · Engine · CA

Started with rough idle then got overheating msg on dashboard. After the diagnostics they found cracked cylinder head and quoted $6000 for replacement. Called Mazda USA and they denied our claim. Car is under 5yrs old & around 74k. While working on the car they noticed the turbo needed it to be rebuilt. Another $2k. There is TSB out for this and it’s a known problem, lot of others having/had same issues. Never had a car that needed an engine replacement even before car is paid off.

Filed Jun 5, 2024 · Engine · VA

In June of 2022, Mazda issued a TSB for an engine flaw that cause coolant to leak in to the engine and significant overheating occurred. This overheating causes the head to warp. The TSB states that the only repair for this is a newer model engine. This happened to my Mazda CX9 and quite a few more. There are class action suits currently ongoing. Mazda never made its owners aware of the TSB. The car can shut down on the highway which is dangerous to all.

Filed Aug 31, 2023 · Engine · AL

The engine is leaking coolant i will be putting a 3rd motor in this car due to other 2 motor also have a coolant leaking and running hot i have contact mazda and would not stand behind there car