2014 Mclaren P1 3.8L Hybrid electric (clean) · LJ64 RXH

The P1's high-voltage hybrid battery and KERS hardware are the car's most expensive electrical components. Owners and specialists have reported hybrid battery failure as early as year two or three of ownership, and because the powertrain is packaged behind the rear body panel, rectification requires major labour as well as a new battery. With the car out of warranty, a replacement has been quoted as a six-figure bill, and the system is sensitive to the car sitting unused for long periods. A failed hybrid system can leave the P1 immobile, so battery health is the first thing a used buyer should verify.

The P1's supplied hybrid battery charger has been known to drain the conventional 12V battery if the car is left connected or unused, and the hybrid system as a whole is sensitive to sitting still. A flat 12V battery can prevent the car from starting and can trigger spurious warning lights across the hybrid and infotainment systems. Because the P1 is often stored for weeks at a time, this is one of the more common electrical niggles for UK used buyers, though a replacement 12V battery is a minor cost compared with the high-voltage pack.

McLaren recalled the P1 (UK/Rest of World campaign, January 2016) because of tolerance build-up in the bonnet secondary latch: if disengaged and re-engaged, the solenoid plunger may miss the latch hole, leaving the secondary latch unable to retain the bonnet, which could open while the car is moving. The remedy is a free replacement of the hood latch. Used buyers must verify the campaign was completed, as an unresolved recall is a serious safety issue at P1 speeds.