Used BMW 840

What to know before buying: BMW 840

From 4 forum threads and 1 press test · updated 12/10/2026

What the reviews say

• A forum describes the E31 840Ci as markedly better than the 850i: improved automatic and electronics, much lower consumption and nearly equal performance, though the suspension still needs attention.[3]one source
• An E31 840 owner describes it as large and heavy but not sluggish: acceleration in Sport is strong, although the automatic hesitates before downshifting.[2]one source
• In a 2019 840i discussion, the B58 six-cylinder is praised for power, smoothness and economy, and judged a more rational everyday choice than the costlier M850i.[4]one source840i (2019–2024)
• Integral active steering noticeably improves 840i agility through bends and roundabouts, although one test driver found its responses overly synthetic.[4]one source840i (2019–2024)

Typical faults

• One 1997 E31 840 drained both batteries after a week parked. Suggested causes included failing batteries, failure to enter sleep mode or a control module drawing current.[1]one source

  1997–1997

• An E31 owner reports that the brake hydraulic accumulator can fail and the hydraulic booster can lose pressure or fluid; his car suffered both leakage and pressure loss.[2]one source
• An E31 forum contributor reports that the headlamp contacts can burn.[2]one source
• Engine overheating is listed as a frequent 2019–2024 840i problem; coolant level, thermostat and radiator should be checked.[5]one source840i (2019–2024)

  2019–2024 · 3.0L Turbo I6

• Low oil-pressure-sensor signal and critically insufficient oil pressure are listed as frequent faults for the 2019–2024 840i.[5]one source840i (2019–2024)

  2019–2024 · 3.0L Turbo I6

• A recall covers certain 2020–2025 840i vehicles because repeated starting attempts can overheat the starter through electrical overload.[5]one source

  2020–2025

Which engine and version to take

• The six-cylinder B58 in the 2019 840i is praised for smoothness, power and economy, making it the rational choice when costs are considered.[4]one source840i (2019–2024)
• A forum rates the E31 840Ci V8 above the 850i powertrain, citing an improved automatic, much lower fuel consumption and nearly equal performance.[3]one source

What to check at the inspection

• On an E31, verify that the selector indicator goes out and the car enters sleep mode after locking; measure standby current and pull fuses individually to locate any drain.[1]one source
• Test both E31 batteries: in one reported case a failed battery drained the entire system within a day, while replacing both batteries cured the fault.[1]one source
• Test the E31 hydraulic accumulator after running the engine for 10 minutes: switch off and repeatedly press the brake; reservoir level should rise for roughly at least 15 presses.[2]one source
• Inspect the E31 hydraulic booster for fluid leakage and verify that it maintains pressure in operation.[2]one source
• Run electronic diagnostics on a 2019–2024 840i, focusing on overheating, oil-pressure, engine-control-module and throttle-actuator faults.[5]one source840i (2019–2024)
• Check whether the specific 840i has completed applicable recalls covering the starter, brakes, battery, seat-belt buckles, camera and power windows.[5]one source840i (2019–2024)

Verdict

Sources

1. [1]autopower.se — Köpråd och information om BMW 840 E31 -97 · forum
2. [2]bmwpower-bg.net — Виж темата - Да ми е честито - БМВ 840 · forum
3. [3]bmwslo.com — Problemi z 850????? - Serija 6, 7 in 8 · forum
4. [4]motor-talk.de — 840i - Seite 2 - Ich hatte noch nie Probleme mit der IAL. ... · forum
5. [5]troubleatlas.com — Bmw 840I (2019–2024) — Maintenance, Battery & Fault Codes · press

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