BMW 801031: Electric Auxiliary Heater (HV) Fault
BMW code 801031 sits in the 801xxx block for the high voltage electric auxiliary heater on plug-in hybrid and EV models, but the exact sub-fault is not publicly documented, so it needs an ISTA diagnostic read on your specific chassis. Related codes in this family point to internal heater faults or coolant temperature sensor readings out of range, and a leaking coolant changeover valve is often mistaken for heater failure.
Quick facts
- System
- Hybrid / HV Auxiliary Heater
- Severity
- Moderate
- Can you still drive?
- Short drives only, diagnose soon
- Applies to
- BMW PHEV and EV with the HV electric auxiliary heater: F30 330e, F10/G30 530e, F15 X5 40e, G12 740e, plus i3/i4/i5/i7 BEV variants of the same component family.
Also shown by some scanners as: 801031, bmw 801031, 801380, 801386
Symptoms
- No or weak cabin heat and slow demist on a plug-in hybrid
- Heater or climate fault message with the HV system otherwise working
- Engine starts more often than expected in cold or damp conditions to make heat
- Coolant loss or damp smell around the HV heater and its hoses
- Reduced electric only range because the engine runs for heating
Common causes, most likely first
- 1
Failed electric auxiliary heater (HV coolant heater) internal element or electronics
Most common cause, but confirm with a proper diagnostic read first
- 2
Leaking coolant changeover valve
Very common cause of no heat that is often misread as heater failure
- 3
Coolant level low or air in the HV heater circuit after a previous repair
- 4
Damaged or corroded HV heater connector and wiring
- 5
Coolant temperature sensor reporting out of range
Seen in a related sibling code, exact link to 801031 unverified
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Frequently asked questions
Can I still drive with BMW code 801031?
The car usually still drives, but this involves a high voltage component and the coolant circuit, so treat it with caution. Drive only to the workshop, keep an eye on coolant level and temperature, and stop immediately if a red HV or overheating warning comes on. Loss of demist is also a visibility risk in wet weather, so get it checked promptly.
Does 801031 always mean the electric auxiliary heater itself is faulty?
Not necessarily. This exact sub-code is not individually documented, and even the closest related codes point to more than one possible cause. A leaking coolant changeover valve, low coolant or air in the circuit, or a wiring or sensor problem can all trigger similar symptoms. A proper diagnostic read on your specific chassis is needed before assuming the heater unit itself needs replacing.
How do I fix BMW code 801031?
Start with an ISTA diagnostic read to confirm the exact sub-fault on your chassis, since this is a high voltage system and Gen5 cars require an HV certified technician. Depending on findings, the fix path usually involves the electric auxiliary heater unit, the coolant changeover valve, HV heater hoses and connector, or the coolant temperature sensor. WhatsApp us the code and car model for stock and today's price.
Which BMW models does code 801031 apply to?
This code applies to BMW plug-in hybrid and EV models fitted with the HV electric auxiliary heater, including F30 330e, F10 and G30 530e, F15 X5 40e, G12 740e, and the i3, i4, i5, i7 BEV variants that share this component family. A BMW service bulletin covers similar heater replacements on newer i4, i5 and i7 BEVs, but it does not confirm this exact code on the F-chassis PHEVs, so chassis specific diagnosis is still needed.
