Why does my Mazda CX-70 PHEV hesitate or show an engine malfunction warning?

Short answer: Most of these early CX-70 PHEV problems were fixed with software. Mazda recalled 2025 models for PCM/ECM and inverter software that can trigger warnings and cut power, and bulletin SA-021/25 covers delayed engine start and weak EV-mode acceleration at low battery charge. Make sure the dealer has done the recalls and the latest calibrations. If you hear a grind on the 1-2 shift, report it while you're under warranty.

Symptom: An engine malfunction or warning message, slow or failed starts, a pause before the gas engine joins in, weak acceleration in EV mode when the battery is low, or a grind on the 1st-2nd shift from a stop.

What to check first

1. Run your VIN for recalls 24V815000 and 24V817000.
2. Ask the dealer whether bulletin SA-021/25 applies to your VIN.
3. Note battery charge level and mode when it hesitates.
4. Record the shift grind (speed, throttle, mode).
5. Get codes read when a warning shows.
6. Run your VIN at nhtsa.gov/recalls.

Likely causes

1. PCM/ECM or inverter software (recalls). The PCM is the powertrain computer and the inverter turns battery power into motor power. Mazda recalled the 2025 CX-70 for software in both that can turn on warning lights and cut drive power. The fix is a free reprogram.
2. Delayed engine start at low battery charge. Mazda bulletin SA-021/25 (shared on the CX-70 owner forum) covers delayed engine start or poor acceleration in EV mode when the battery charge is low, caused by PCM control logic. The fix is a PCM software update.
3. 1st-2nd shift grind or clunk. The CX-70 uses a clutch instead of a torque converter in its 8-speed automatic, so shifts can feel firmer. Several owners hear a grind on hard launches. One CX-90 owner said theirs ended in a transmission replacement.

What it usually costs

Software updates under recall or warranty are free. Owners didn't post out-of-warranty prices.

Is it safe to keep driving?

Loss of drive power can be dangerous in traffic. If you get a warning with reduced power, pull over safely and call the dealer. Don't put off the software recalls.

DIY or shop?

Nothing to DIY beyond reading codes. An EV's or plug-in hybrid's high-voltage system can stay live with the car off. Leave the orange cables, the big battery and the charging hardware to a trained EV technician.

Recalls, bulletins and complaints in plain words

• Recalls and bulletins: NHTSA lists 4 recalls for the 2025 CX-70: 24V815000 (PCM/ECM software may turn on warning lights and cause loss of drive power, fix is a free reprogram), 24V817000 (PHEV inverter software may cause loss of drive power in EV mode), 24V814000 (electrical supply unit at startup) and 25V568000 (mild hybrid fuel gauge reading). Mazda bulletin SA-021/25 covers delayed engine start in EV mode. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 19 keyword-matched complaints for Mazda CX-70 2025–2026 (of 56 unique complaints queried, NHTSA complaints API by model year, queried 2026-11-02; keywords: hesitat, accelerat, delay, engine malfunction, start, power, stall, shift) (NHTSA returned no data for 1 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Engine malfunction CX70 PHEV on Reddit r/mazda, a CX-70 PHEV bought in October wouldn't start on the first three tries, then showed an engine malfunction message. The dealer did two software updates and it was fine afterward. Replies said many early issues were fixed with PCM and other module updates, and one quoted the bulletin about loss of motor power in EV mode from inverter software.
• In DELAYED ENGINE START or POOR ACCELERATION WHILE DRIVING IN EV MODE on Mazda CX-70 Forum, owners shared Mazda bulletin SA-021/25 for 2025 CX-70 PHEVs built before October 16, 2024. It covers delayed engine start and poor acceleration in EV mode at low battery charge, and the fix is a PCM software update (with related ECM and TCM updates listed).
• In CX-70 Transmission Issue on Reddit r/mazda, a CX-70 PHEV with under 300 miles made a grinding sound on the 1st-2nd shift when accelerating quickly from a stop, in both EV and hybrid mode. Mazda's hotline was involved. Other owners said theirs did the same, one said theirs sometimes wouldn't shift out of Park until restarted, and a CX-90 PHEV owner said theirs ended with a transmission replacement.

Quick tip

Make sure every software recall and update is done. That fixed it for most owners.

Vehicle focus: Mazda CX-70 PHEV, 2025-2026 (shares its powertrain with the CX-90 PHEV).

Safety / mechanic note

Loss of drive power is a crash risk. Verify with a mechanic.