My Chevy Blazer EV says "Service High Voltage System." What fixes it?

Short answer: On a Blazer EV, Service High Voltage System often points to the A/C refrigerant system, which also cools the battery. Owners' fixes were a bad refrigerant pressure sensor, a leaking line connector, or a recharge. GM's bulletin PIT6112C (code P0534) tells dealers to update software, then evacuate and refill the A/C. Also ask about Service Update N232401570. It's warranty work, so book the dealer even if the warning clears itself.

Symptom: 'Service High Voltage System' on the dash, sometimes with no heat, slow or no charging, or warnings that come and go in cold weather.

What to check first

1. Note whether heat and A/C still work and the outside temperature when it happened.
2. Ask the dealer about GM bulletin PIT6112C and code P0534.
3. Ask whether Service Update N232401570 applies to your VIN.
4. Ask them to leak-check the A/C and test the refrigerant pressure sensors.
5. Run your VIN at nhtsa.gov/recalls.

Likely causes

1. A/C refrigerant leak or bad A/C sensor. The A/C system also cools the high-voltage battery, so a low charge or bad pressure sensor can trigger this warning. GM Preliminary Information PIT6112C covers 2023-2024 Lyriq, 2024-2025 Blazer EV and 2024-2025 Equinox EV with a Service High Voltage System message and code P0534 (high-voltage charging not working). It says the cause is the refrigerant (A/C) system not working as intended. Dealers update the BCM and BECM software if available, then evacuate and refill the A/C, and look for leaks with a black light if the charge comes back short.
2. Battery control software (BECM/CMU). An owner shared GM Service Update N232401570 for some Blazer EVs. It isn't a safety recall. It fixes a case where the battery control module (BECM) won't finish starting up because it thinks a cell monitoring unit (CMU) is offline.
3. Cold-weather temperature faults. Some owners saw the warning after the car sat outside in the cold, and it cleared itself later.

What it usually costs

Owners had these repaired under warranty and didn't post prices.

Is it safe to keep driving?

Limited. Owners lost heat and charging, and one was stranded far from home. Get it to the dealer soon.

DIY or shop?

Nothing here is DIY beyond noting symptoms. An EV's high-voltage system can stay live with the car off. Leave the orange cables, the big battery and the drive unit to a trained EV technician.

Recalls, bulletins and complaints in plain words

• Bulletin: GM Preliminary Information PIT6112C covers 2023-2024 Lyriq, 2024-2025 Blazer EV and 2024-2025 Equinox EV with a Service High Voltage System message and code P0534 (high-voltage charging not working). It says the cause is the refrigerant (A/C) system not working as intended. Dealers update the BCM and BECM software if available, then evacuate and refill the A/C, and look for leaks with a black light if the charge comes back short. NHTSA also lists 6 recalls for the Blazer EV in these years, including 24V320000: rear drive motors on some 2024 GM EVs may have insufficiently insulated wires. 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: 18 keyword-matched complaints for Chevrolet Blazer EV 2024–2025 (of 99 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-31; keywords: high voltage, charg, heat, 12 v, battery, stranded, loss of power). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Our Service High Voltage Battery Error Resolved on Reddit r/BlazerEV, after seven shop visits over five months, a Blazer EV's Service High Voltage errors were traced to a bad refrigerant pressure sensor under the hood and a refrigerant line with a malformed connector that was leaking. Replacing both and recharging the system fixed it.
• In UPDATE: Stranded 450 miles from home, no heat / service high voltage issue. on Reddit r/BlazerEV, an owner stranded 450 miles from home with no heat and a Service High Voltage warning said the dealer found the A/C system low, which upset battery cooling. They replaced some sensors and recharged it. Another owner said they had the high-pressure A/C sensors replaced.
• In UPDATE to my previous "SERVICE HIGH VOLTAGE". Its.. gone suddenly? on Reddit r/BlazerEV, an owner's Service High Voltage warning cleared itself after a cold spell of 15-30F. The dealer found only stored temperature faults and advised avoiding extreme temperatures. Another owner said theirs cleared itself twice, and once the dealer worked on the heat pump.
• In Having "Service High Voltage System" issues? Try this. on Reddit r/BlazerEV, an owner shared GM Service Update N232401570 for some Blazer EVs. It's not a safety recall. It updates the battery control software when the BECM thinks a cell monitoring unit is offline.

Quick tip

Write down the temperature and what stopped working each time it happens. Intermittent faults get fixed faster with a clear log.

Vehicle focus: Chevrolet Blazer EV, 2024-2025.

Safety / mechanic note

Losing heat or drive power is a safety risk. Verify with a mechanic.