2021 Mazda CX-5 reported problems

The records describe a problem worth checking before purchase.

“..... ON AT LEAST 5 SEPERATE OCCASIONS OUR 2021 MAZDA CX5 SUV ACCELERATED TO A HIGH RATE OF SPEED (ON IT'S OWN). IT HAS DONE IT TO MY WIFE AND I BOTH. I CONTACTED TWO DIFFERENT MAZDA SERVICE CENTERS AND WAS ADVISED THEY HAVE NO KNOWLEDGE OF THIS AND THAT THERE ARE NO OPEN RECALLS OR TSB's AND AS INTERMITTENT AS IT IS IT WOULD BE ALMOST IMPOSSIBLE TO DUPLICATE. ON JULY 18TH THE CAR ACCELERATED (ON ITS OWN) AGAIN BUT THIS TIME IT DROVE MY WIFE INTO A TREE AT APROX. 35/40 MPH BREAKING HER RIBS. THE BODY SHOP INFORMED ME THIS MORNING THAT THE CAR IS A TOTAL LOSS. MAZDA NEEDS TO GET TO THE BOTTOM OF THIS AND RESOLVE THIS ISSUE ASAP. THIS TIME IT WAS A TREE, THE NEXT TIME IT MAY BE AT A CROSSWALK OR AT AN INTERSECTION. IT'S JUST A MATER OF TIME UNTIL SOMEONE IS KILLED OR AT THE VERY LEAST BADLY HURT. I DON'T KNOW HOW MAZDA CAN BE UNAWARE OF THIS PROBLEM, IT'S ALL OVER THE INTERNET. OUR BODY SHOP PULLED IT UP ON LINE AND WAS SHOCKED AT THE AMOUNT OF COMPLAINTS/ CONCERNS THAT EXISTED RELATED TO THIS PROBLEM. PLEASE INVESTIGATE THIS BECAUSE THE NEXT PERSON MAY NOT BE AS FORTUNATE. THANK YOU IN ADVANCE.”

The records describe a problem worth checking before purchase.

“The vehicle's Connectivity Master Unit (CMU) suffers from a severe, persistent electronic hardware malfunction that causes the central information display and dashboard telemetry to blink, cycle, and drop signals erratically. This specific hardware architecture failure threatens to corrupt data transmission lines directly connected to the Advanced Driver Assistance System (ADAS), creating an imminent safety risk of unintended automatic emergency braking or false sensor deployment during highway transit. The vehicle utilizes the exact same defective CMU hardware component that the manufacturer has acknowledged and recalled on other model cohorts; however, the manufacturer has explicitly excluded this specific VIN from safety recall eligibility. Diagnostic attempts by the authorized dealer network relied solely on forcing digital software updates that completely failed to correct the core hardware signaling instability, leaving the vehicle un-repaired and presenting an active, unmitigated electrical and safety hazard on public roads.”

The records describe a problem worth checking before purchase.

“Radio audio randomly stopped working and you have to disconnect the negative or you have to leave the car off essentially all night. It’s definitely unknown issue there’s videos all over YouTube about it and there’s forms on read about it.”

The records describe a problem worth checking before purchase.

“On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat installed inside of the suspected coolant control valve on certain 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6 and 2020-2023 CX-30 vehicles. The warranty coverage for an applicable repair has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. If you are a recipient of this notice, your vehicle is included in this warranty extension program. What is the problem? On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat installed inside of the suspected coolant control valve on certain 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6 and 2020-2023 CX-30 vehicles. The warranty coverage for an applicable repair has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. If you are a recipient of this notice, your vehicle is included in this warranty extension program. What is the problem? On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“Mazda Motor Corporation has decided to conduct a Special Service Program (SSP) to extend the warranty coverage for a specific repair of the fail-safe thermostat installed inside of the suspected coolant control valve on certain 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6 and 2020-2023 CX-30 vehicles. The warranty coverage for an applicable repair has been extended to 15 years (180 months) /150,000 miles (240,000 km) whichever comes first, from the original warranty start date. If you are a recipient of this notice, your vehicle is included in this warranty extension program. What is the problem? On certain subject vehicles, the check engine light is illuminated with diagnostic trouble code (DTC) P0126, due to the fail-safe thermostat being stuck open. Additionally, you may notice one or more of the following symptoms: -Engine takes longer to warm up. -Engine temperature gauge fluctuates. -Low coolant temperature indicator (blue) light stays on longer or turns on while driving. -Poor heater performance, especially at idle. This warranty extension program applies only to the replacement of fail-safe thermostat of the vehicle exhibiting the concerns mentioned above. If the check engine light illumination is determined to be unrelated to the fail-safe thermostat being stuck open, the inspection and repair are not covered under this program.”

The records describe a problem worth checking before purchase.

“SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while driving. - Poor heater performance, especially at idle. Mazda Motor Corporation has made a significant repair change to TSB 01-003/25 which also impacts Warranty Extension Special Service Program (SSPD8). Repair Procedure Update: Effective December 8th all repairs applicable to TSB 01-003/25 or SSPD8 must follow the new repair procedure. The repair now replaces the thermostat with a dummy plug for the coolant control valve (CCV) along with a required software update for the PCM. Prior Repairs: Any repairs previously completed with the replacement of the thermostat or coolant control valve assembly does not require a re-repair unless there is a verified failure following the diagnosis in the TSB. It is expected that there will be no further repairs made for this concern once the plug and software update has been completed. Therefore, a return visit for symptoms related to the TSB or SSP must contact the Technical Hotline for assistance. VITALLY IMPORTANT!: There must be a “Software Update” record for the PCM when using MDARS or IDS. • MDARS - If there is no Software Update entry in MDARS or the Collect Diagnostic Information (ODR Update) is not completed (or both), the vehicle will not be considered repaired and the warranty claim will be rejected. • IDS – Vehicles programed with IDS must Collect Diagnostic Data, and that data must be attached to the warranty claim. If the data is not attached to the claim, the vehicle will not be considered repaired and the warranty claim will be rejected, denied or debited. Failure to complete the above will require the vehicle to return to the dealership and be re-repaired at the dealer’s expense with great inconvenience to the Mazda customer. Failure to perform the software update could also potentially damage the engine which would not be covered by warranty and would expose your dealership to the cost of repairs. ”

The records describe a problem worth checking before purchase.

“SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while driving. - Poor heater performance, especially at idle. Mazda Motor Corporation has made a significant repair change to TSB 01-003/25 which also impacts Warranty Extension Special Service Program (SSPD8). Repair Procedure Update: Effective December 8th all repairs applicable to TSB 01-003/25 or SSPD8 must follow the new repair procedure. The repair now replaces the thermostat with a dummy plug for the coolant control valve (CCV) along with a required software update for the PCM. Prior Repairs: Any repairs previously completed with the replacement of the thermostat or coolant control valve assembly does not require a re-repair unless there is a verified failure following the diagnosis in the TSB. It is expected that there will be no further repairs made for this concern once the plug and software update has been completed. Therefore, a return visit for symptoms related to the TSB or SSP must contact the Technical Hotline for assistance. VITALLY IMPORTANT!: There must be a “Software Update” record for the PCM when using MDARS or IDS. • MDARS - If there is no Software Update entry in MDARS or the Collect Diagnostic Information (ODR Update) is not completed (or both), the vehicle will not be considered repaired and the warranty claim will be rejected. • IDS – Vehicles programed with IDS must Collect Diagnostic Data, and that data must be attached to the warranty claim. If the data is not attached to the claim, the vehicle will not be considered repaired and the warranty claim will be rejected, denied or debited. Failure to complete the above will require the vehicle to return to the dealership and be re-repaired at the dealer’s expense with great inconvenience to the Mazda customer. Failure to perform the software update could also potentially damage the engine which would not be covered by warranty and would expose your dealership to the cost of repairs. ”

The records describe a problem worth checking before purchase.

“SSPD8 - Check Engine Light ON with DTC P0126:00 - WARRANTY EXTENSION For certain 2018-2025MY CX-5, 2019-2023MY Mazda3, 2019-2022MY CX-3, 2018-2021MY Mazda6, 2020-2023MY CX-30 that are equipped with the suspected coolant control valve, the warranty coverage for specific repair of the fail-safe thermostat is extended to: 15 years (180 months) or 150,000 miles (240,000 km) whichever comes first, from the original warranty start date. CONDITION OF CONCERN: On certain subject vehicles, the check engine light is illuminated with DTC P0126:00 (Thermostat stuck open) stored in memory and one or more of the following symptoms may occur: - Engine takes longer to warm up. - Engine temperature gauge fluctuates. - Low coolant temperature indicator (blue) light stays on longer or turns on while driving. - Poor heater performance, especially at idle. Mazda Motor Corporation has made a significant repair change to TSB 01-003/25 which also impacts Warranty Extension Special Service Program (SSPD8). Repair Procedure Update: Effective December 8th all repairs applicable to TSB 01-003/25 or SSPD8 must follow the new repair procedure. The repair now replaces the thermostat with a dummy plug for the coolant control valve (CCV) along with a required software update for the PCM. Prior Repairs: Any repairs previously completed with the replacement of the thermostat or coolant control valve assembly does not require a re-repair unless there is a verified failure following the diagnosis in the TSB. It is expected that there will be no further repairs made for this concern once the plug and software update has been completed. Therefore, a return visit for symptoms related to the TSB or SSP must contact the Technical Hotline for assistance. VITALLY IMPORTANT!: There must be a “Software Update” record for the PCM when using MDARS or IDS. • MDARS - If there is no Software Update entry in MDARS or the Collect Diagnostic Information (ODR Update) is not completed (or both), the vehicle will not be considered repaired and the warranty claim will be rejected. • IDS – Vehicles programed with IDS must Collect Diagnostic Data, and that data must be attached to the warranty claim. If the data is not attached to the claim, the vehicle will not be considered repaired and the warranty claim will be rejected, denied or debited. Failure to complete the above will require the vehicle to return to the dealership and be re-repaired at the dealer’s expense with great inconvenience to the Mazda customer. Failure to perform the software update could also potentially damage the engine which would not be covered by warranty and would expose your dealership to the cost of repairs.”

The records describe a problem worth checking before purchase.

“Subject: TSB 01-001/26 Warranty and Parts Kit Update INCLUDES: Warranty Extension Program - Special Service Program (SSP) D8 Check Engine Light ON with DTC P0126:00, 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6, 2020-2023 CX-30 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has made a change regarding related parts to TSB 01-001/26 which also impacts Warranty Extension Special Service Program (SSPD8). Parts Ordering and Warranty Claims: Effective March 5, 2026 only the related parts kit PYY2-15-SAY can be ordered and claimed for any repair. The two separate parts PYFB-15-169 and PE13-15-296 can no longer be claimed with repaired dates of March 5, 2026 and later. There is no change to the main part, the Plug PYY3-15-SA1. We have updated the TSB 01-001/26 and SSPD8 Repair Procedure and Parts & Warranty Information on Mazda Global Service Support (MGSS) to reflect this change. ”

The records describe a problem worth checking before purchase.

“Subject: TSB 01-001/26 Warranty and Parts Kit Update INCLUDES: Warranty Extension Program - Special Service Program (SSP) D8 Check Engine Light ON with DTC P0126:00, 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6, 2020-2023 CX-30 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has made a change regarding related parts to TSB 01-001/26 which also impacts Warranty Extension Special Service Program (SSPD8). Parts Ordering and Warranty Claims: Effective March 5, 2026 only the related parts kit PYY2-15-SAY can be ordered and claimed for any repair. The two separate parts PYFB-15-169 and PE13-15-296 can no longer be claimed with repaired dates of March 5, 2026 and later. There is no change to the main part, the Plug PYY3-15-SA1. We have updated the TSB 01-001/26 and SSPD8 Repair Procedure and Parts & Warranty Information on Mazda Global Service Support (MGSS) to reflect this change. ”

The records describe a problem worth checking before purchase.

“Subject: TSB 01-001/26 Warranty and Parts Kit Update INCLUDES: Warranty Extension Program - Special Service Program (SSP) D8 Check Engine Light ON with DTC P0126:00, 2018-2025 CX-5, 2019-2023 Mazda3, 2019-2022 CX-3, 2018-2021 Mazda6, 2020-2023 CX-30 Dear Mazda Dealer Colleagues, Mazda Motor Corporation has made a change regarding related parts to TSB 01-001/26 which also impacts Warranty Extension Special Service Program (SSPD8). Parts Ordering and Warranty Claims: Effective March 5, 2026 only the related parts kit PYY2-15-SAY can be ordered and claimed for any repair. The two separate parts PYFB-15-169 and PE13-15-296 can no longer be claimed with repaired dates of March 5, 2026 and later. There is no change to the main part, the Plug PYY3-15-SA1. We have updated the TSB 01-001/26 and SSPD8 Repair Procedure and Parts & Warranty Information on Mazda Global Service Support (MGSS) to reflect this change. ”