Volvo S90 T8 Recharge SPA

The ERAD unit provides rear-wheel drive and is a documented weak point on all Volvo T8 PHEVs. Three generations exist: ERAD1 (2016-2017, Siemens-made) is the most failure-prone with clutch mechanism and thermal sensor issues. ERAD2 (2018-2021) introduced more resilient internal components but retains the clutch mechanism. ERAD3 (from mid-2022, Schaeffler-made) replaced the clutch pack entirely with a permanently engaged planetary gearbox and is significantly more reliable. Failures on ERAD1 and ERAD2 typically appear between 50,000 and 120,000 km. Symptoms include grinding, clicking, or knocking from the rear axle, hesitation under acceleration, and eventually complete loss of rear electric drive. A gear rebuild costs around €3,500 at a specialist, while full ERAD replacement runs €6,000-8,000 at a Volvo dealer. Independent specialists who work on ERADs remain very rare. Volvo extended the ERAD warranty to 5 years in some markets. Repeat failures have been documented even after rebuild.

Volvo recalled approximately 73,000 T8 PHEV vehicles worldwide (2020-2022 model years) after identifying that high-voltage battery modules with LG-supplied cells (produced June 2019 to November 2021) could short circuit when the battery is fully charged and the car is parked. This is a serious safety issue with potential thermal runaway risk. Volvo inspects and replaces affected battery modules free of charge and installs diagnostic monitoring software. Owners were initially advised not to charge above 70% until the recall was completed. The repair itself is free, but an unresolved recall is a deal-breaker for purchase. Verify with Volvo using the VIN that this recall has been fully completed before purchasing any 2020-2022 T8 model.

The HVCH provides cabin heating when the car operates in pure electric mode. Failures have been reported across all T8 model years and the part has been on significant backorder at times. When the HVCH fails, the combustion engine must run for cabin heat, eliminating the benefit of electric-only driving in cold weather. The component costs approximately €1,000-1,200, with labor adding €400-800 due to its location behind the right front fender liner. Diagnosis alone can cost €300-400 at a dealer. Some owners have experienced repeated HVCH failures after replacement, suggesting a design limitation in certain operating conditions.

This is a known SPA-platform issue affecting all Volvo models on this architecture. The AC evaporator can freeze and crack due to the climate control system overcooling the core. Replacement requires removing the seats, center console, steering column, and entire dashboard assembly, making it a 12-15 hour labor job. Total repair cost at a dealer is typically €2,500-4,000. A preventive resistor harness (Volvo part 32241228) installed in the cabin temperature sensor circuit can prevent the overcooling that causes the failure. If the car's AC currently works normally, having this resistor fitted is an inexpensive preventive measure (approximately €50-100 for parts and installation).

Pre-2022 T8 models use both a turbocharger and a supercharger (twincharged). The supercharger engages below approximately 3,500 rpm before handing off to the turbo. Failures typically manifest as a slight power delay that worsens in hot weather or with the AC running. The supercharger is not fed by engine oil; instead it uses its own sealed lubrication. Volvo recommends letting the engine idle briefly after hard driving to allow the supercharger to cool properly rather than shutting off immediately. Replacement costs €1,200-2,200 including parts and labor. This issue does not affect 2022+ models where the supercharger was eliminated from the drivetrain in favor of a more powerful rear electric motor.

The T8 PHEV draws significant standby current from the 12V battery through its various electronic modules. The 12V battery is charged from the high-voltage battery via a DC-DC converter; there is no traditional alternator. If the high-voltage battery is depleted or the car sits unused for extended periods, the 12V system can drain within 7-14 days. In rare cases, a faulty CEM (Central Electronic Module) draws excessive current (up to 15 amps when normal draw should be under 1 amp), requiring CEM replacement at €400-800. Keeping the car locked activates sleep mode after 30 minutes, reducing draw. Using a trickle charger or keeping the car plugged in prevents most drain issues. Battery replacement itself costs €200-500 for a quality AGM unit.

The Sensus infotainment system on pre-2023 S90 models is prone to intermittent freezing, blackout, or slow response. Because nearly all vehicle functions run through the touchscreen (including climate control and heated seats), a screen failure is more disruptive than in cars with physical backup controls. Most freezes can be resolved with a soft reset (holding the Home button for 20-30 seconds) or by locking the car for 30 minutes to trigger sleep mode. Volvo released multiple software updates that improved stability on 2018+ models. In severe cases, the CEM or the display unit itself needs replacement at €800-1,500. From 2023, the switch to Google-based infotainment largely resolved these legacy issues, though early Google OS builds had their own teething problems.