MG MG4 SEH3 — Problems & Common Faults
Weaknesses, engine ratings and buying advice
The MG4 (SEH3) has been MG's first volume all-electric compact car sold in Europe since September 2022, built on the in-house Modular Scalable Platform with rear-wheel drive as the standard layout. The lineup ranges from the Standard with a small 51 kWh pack through the Comfort/Luxury version with 64 kWh up to the Extended Range with 77 kWh, joined since 2023 by the twin-motor all-wheel-drive XPower with up to 320 kW system output. A facelift arrived in March 2026 with a reworked cockpit, a new power lineup (140/180/320 kW) and better interior material quality.
Technically the picture is mixed. The electric motors themselves are considered robust and unobtrusive; the weak points sit mainly in the electrical system and the software. Repeatedly documented is a failure of the automatic recharging of the 12V battery, which in the worst case leaves the car completely stranded - a fault pattern workshops now recognise, though it is not always fixed on the first visit. Heating and air-conditioning control also cuts out sporadically on some cars, usually after several unsuccessful workshop visits. On the software side there are recurring teething problems: a freezing infotainment system, an adaptive cruise control that brakes hard for no visible reason, and various smaller bugs affecting the camera and speedometer display. On the plus side, updates are carried out free of charge under the seven-year warranty, though only once a fault is reported to a dealer; there is no over-the-air update.
The battery variants differ in cell chemistry: the Standard and the 64 kWh facelift version use lithium iron phosphate, while Comfort/Luxury, Extended Range and XPower use nickel manganese cobalt. The LFP cells are more sensitive to cold while charging and, in long-term evaluations so far, even show a slightly faster capacity loss than the NMC variants - contrary to the usual expectation for this chemistry. The manufacturer warranty covers the high-voltage battery for 84 months or 150,000 km, with a 70 percent capacity threshold.
When buying used, it is worth taking a close look at the service and update history: many of the known issues have been eased with newer software levels, while cars that were never updated often still carry the old quirks. A quick functional check of heating and air conditioning at a realistic temperature, a test drive with cruise control engaged, and a look into the side boot compartments for moisture are all advisable. The Comfort/Luxury with the 64 kWh NMC pack is a solid compromise of range and price, while the Extended Range suits high-mileage drivers. Despite its impressive performance, the XPower is not a sports car in the classic sense but a strongly motorised everyday car with a soft base tune - occasionally reported vibrations between 90 and 120 km/h are usually resolved by wheel balancing or replacing rubber mounts. Overall the MG4 offers a lot of car for the money but demands some patience with the electronics.
Engine Overview
The MG MG4 SEH3 is available with 5 engine variants — from 170 to 435 hp.
The permanently excited synchronous motor on the rear axle works unobtrusively in daily use and delivers sufficient pull without standing out through vibration or unusual noise. Depending on the battery variant, either lithium iron phosphate or nickel manganese cobalt cell chemistry is used; both react differently to cold and sustained load, so checking the charging history and condition is worthwhile when buying used. The power electronics and onboard electrical system are the more sensitive assemblies: software levels differ considerably between cars, updates must be triggered by a dealer, there is no automatic over-the-air update. A functioning DC/DC converter to the 12V battery is essential, since without it the entire electrical system can be disabled. Mechanically the drive unit is built robustly; the weak points lie more in the control software and auxiliary components than in the motor itself.
- !! Unexpected 12V electrical system shutdown
The automatic recharging of the 12V battery via the DC/DC converter fails on some cars. This leads either to a complete standstill of all functions while parked, or more rarely to a brief loss of drive power while underway.
Symptoms: Car cannot be unlocked or started, no warning light reacts at all; more rarely a brief loss of propulsion at higher speed, drivable again normally after a restart.
The permanently excited synchronous motor on the rear axle works unobtrusively in daily use and delivers sufficient pull without standing out through vibration or unusual noise. Depending on the battery variant, either lithium iron phosphate or nickel manganese cobalt cell chemistry is used; both react differently to cold and sustained load, so checking the charging history and condition is worthwhile when buying used. The power electronics and onboard electrical system are the more sensitive assemblies: software levels differ considerably between cars, updates must be triggered by a dealer, there is no automatic over-the-air update. A functioning DC/DC converter to the 12V battery is essential, since without it the entire electrical system can be disabled. Mechanically the drive unit is built robustly; the weak points lie more in the control software and auxiliary components than in the motor itself.
- !! Unexpected 12V electrical system shutdown
The automatic recharging of the 12V battery via the DC/DC converter fails on some cars. This leads either to a complete standstill of all functions while parked, or more rarely to a brief loss of drive power while underway.
Symptoms: Car cannot be unlocked or started, no warning light reacts at all; more rarely a brief loss of propulsion at higher speed, drivable again normally after a restart.
The permanently excited synchronous motor on the rear axle works unobtrusively in daily use and delivers sufficient pull without standing out through vibration or unusual noise. Depending on the battery variant, either lithium iron phosphate or nickel manganese cobalt cell chemistry is used; both react differently to cold and sustained load, so checking the charging history and condition is worthwhile when buying used. The power electronics and onboard electrical system are the more sensitive assemblies: software levels differ considerably between cars, updates must be triggered by a dealer, there is no automatic over-the-air update. A functioning DC/DC converter to the 12V battery is essential, since without it the entire electrical system can be disabled. Mechanically the drive unit is built robustly; the weak points lie more in the control software and auxiliary components than in the motor itself.
- !! Unexpected 12V electrical system shutdown
The automatic recharging of the 12V battery via the DC/DC converter fails on some cars. This leads either to a complete standstill of all functions while parked, or more rarely to a brief loss of drive power while underway.
Symptoms: Car cannot be unlocked or started, no warning light reacts at all; more rarely a brief loss of propulsion at higher speed, drivable again normally after a restart.
The permanently excited synchronous motor on the rear axle works unobtrusively in daily use and delivers sufficient pull without standing out through vibration or unusual noise. Depending on the battery variant, either lithium iron phosphate or nickel manganese cobalt cell chemistry is used; both react differently to cold and sustained load, so checking the charging history and condition is worthwhile when buying used. The power electronics and onboard electrical system are the more sensitive assemblies: software levels differ considerably between cars, updates must be triggered by a dealer, there is no automatic over-the-air update. A functioning DC/DC converter to the 12V battery is essential, since without it the entire electrical system can be disabled. Mechanically the drive unit is built robustly; the weak points lie more in the control software and auxiliary components than in the motor itself.
- !! Unexpected 12V electrical system shutdown
The automatic recharging of the 12V battery via the DC/DC converter fails on some cars. This leads either to a complete standstill of all functions while parked, or more rarely to a brief loss of drive power while underway.
Symptoms: Car cannot be unlocked or started, no warning light reacts at all; more rarely a brief loss of propulsion at higher speed, drivable again normally after a restart.
The all-wheel-drive variant uses two permanently excited synchronous motors, one per axle, so power delivery feels noticeably more spontaneous than in the single-motor version. Mechanically the concept is considered solid; the added complexity sits mainly in the software that manages torque distribution between the two axles. The cells follow the nickel manganese cobalt chemistry of the stronger rear-drive versions and should be cared for accordingly, particularly regarding extended standing time at a high state of charge. Components such as bearings and drivetrain mounting points are put under greater strain by the high power output, so noises or vibrations under brisk driving should be checked at a workshop early on. The power electronics and onboard electrical system basically share the same weak points as the single-motor model.
- !! Unexpected 12V electrical system shutdown
The automatic recharging of the 12V battery via the DC/DC converter fails on some cars. This leads either to a complete standstill of all functions while parked, or more rarely to a brief loss of drive power while underway.
Symptoms: Car cannot be unlocked or started, no warning light reacts at all; more rarely a brief loss of propulsion at higher speed, drivable again normally after a restart. - ! Vibrations in the 90 to 120 km/h speed range
On some all-wheel-drive cars, noticeable vibrations occur between roughly 90 and 120 km/h. Tyre imbalance and/or aged rubber mounts are considered the cause, checked and replaced under warranty by the dealer when needed.
Symptoms: Clearly noticeable vibration in the steering wheel and body at a constant 90 to 120 km/h, barely perceptible at other speeds.
Compare across all models: Replacement costRiskMeasured ageing
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Heating and air conditioning fail sporadically On several cars, heating or cooling cuts out completely at times, even though the fan still spins up normally. Workshops repeatedly replace temperature sensors and install software updates without permanently fixing the problem. Symptoms: Only outside air comes through regardless of the set temperature, neither warm nor cold; the fault occurs irregularly and often cannot be reproduced on demand at the workshop. | Low |
Test Reports
ADAC Autotest
ADAC rated the MG4 Electric Luxury at 2.3 and the MG4 Electric Extended Range Trophy at 2.2 in its road test. The first generation's Euro NCAP crash test scored 84 out of 100 points (5 stars).
2024What Car? Reliability Survey 2025
What Car? Reliability Survey 2025 (UK owner survey, cars up to five years old): reliability rating 89.3%, rank 24 of 32 in the family cars class (class average 92.0%).
2025-10What Car? Reliability Survey 2025
What Car? Reliability Survey 2025 (UK owner survey, cars up to five years old): reliability rating 89.3%, rank 12 of 19 in the electric cars class (class average 90.1%).
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Known Problems and Issues +
A total of 8 weaknesses have been documented for the MG MG4 SEH3 (2022–2026) — 3 engine-related and 5 vehicle-related. Typical issues affect HVAC, Electronics, Body, Interior. Considered reliable: MG4-EM-RWD (Elektromotor), MG4-EM-AWD (Elektromotor (Dual)).
What to watch out for with the MG MG4? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the MG MG4 SEH3 have? +
What should I look for when buying a used MG MG4 SEH3? +
Which engine is recommended? +
Which MG MG4 SEH3 engine is the most reliable? +
Which MG MG4 SEH3 engine is the most fun? +
Is the MG MG4 SEH3 worth buying used? +
What horsepower variants are available for the MG MG4 SEH3? +
Last updated: February 2026 · All information without guarantee