Premium executive sedan popular with business users across Europe. The B47 diesel is significantly more reliable than the older N47, with the timing chain relocated to the front for easier servicing. Main concerns are DPF/EGR system failures (especially on short-trip driving patterns), suspension wear beyond 60,000 km, AdBlue sensor issues, and battery drain if not driven regularly. The G30 is quieter and more refined than competitors, but diesel models show lower reliability scores than petrol variants. Verify EGR recall (2015-2016 production) completed before purchase.
Diesel particulate filter clogs on short trips without highway regeneration · more· less
The DPF can become clogged if the car is driven mostly in short trips without sufficient highway driving to allow for proper regeneration. Symptoms include reduced power, warning lights on the dashboard, or limp mode. In severe cases, forced regeneration (€150-300 at specialist) or DPF replacement might be necessary. A new DPF costs €1,200-1,800 for parts, plus €400-700 labor. Regular highway driving for 20-30 minutes at higher speeds helps prevent this issue. This is particularly common on cars used for city commuting only.
EGR valve/cooler failure€600 - €2,400
EGR system clogging causes poor performance, potential fire risk on 2015-2016 models · more· less
The EGR valve and cooler are known trouble spots for the B47 engine, sometimes leading to recalls. BMW issued a technical campaign for N47, B47 and N57 engines (April 2015 - September 2016 production) due to potential fire risk from EGR cooler leaks. The EGR valve costs around €160 for the part, but labor can be 2+ hours. Complete EGR cooler replacement including intake manifold can reach €1,800 for parts plus €600+ labor. Symptoms include poor acceleration, increased emissions, rough idle, and in severe cases, heat damage to the intake manifold. Regular cleaning helps prevent buildup.
Front control arms and bushings wear between 60,000-100,000 km causing clunking · more· less
Warranty data shows that suspension faults are the single most common type of repair claim on 2017-2023 5 Series models. On the road, this shows up as knocking or clunking over bumps, slightly vague steering, or uneven tire wear. Typical fixes include replacing front control arms/bushings (€185 each at dealer, €50 for bushings), anti-roll bar links, and top mounts. Independent shops charge €400-600 for control arm replacement per side including labor (1-3 hours). Dealers charge 30% more. OE-quality aftermarket parts (TRW, Lemforder) are available at lower cost. The average 5 Series suspension repair in the UK costs £204 (€240).
AdBlue system sensor failure€800 - €2,000
NOx sensor or AdBlue tank sensor fails, triggering check engine light and reduced performance · more· less
Common fault codes include 2C3000, 805278, 80527A, 8052A6. Owners report "AdBlue system faulty" messages despite having a nearly full tank. Problems usually indicate a failed NOx sensor, degraded SCR catalyst, poor AdBlue quality, or wiring loom chafing. Dealer repair costs for NOx sensor plus catalyst run €1,200-1,800. AdBlue tank replacement with sensor costs €1,150-1,300 including labor. In the USA, there is a 10-year warranty on this system. Some owners have successfully pressured BMW Europe for goodwill contributions on common faults. Regular AdBlue fluid refills at BMW cost €1.80 per liter.
Battery drain while parked€150 - €400
Modules fail to enter sleep mode, battery dies within 7-10 days if not driven · more· less
This is described as "a common and KNOWN issue" across BMW forums. Modern BMWs depend heavily on software-controlled modules. When a system fails to enter sleep mode, it continues to draw power even after shutdown. Common sources include infotainment, door sensors, Bluetooth modules, or Comfort Access system. Normal current draw should be 0.03-0.06 amp per hour in sleep mode. One owner found that Bluetooth phone staying connected prevented sleep mode. Solution: use a quality trickle charger (CTEK MXS 5.0 recommended, €60-80) if the car isn't driven for more than 3-4 days. BMW dealers recommend locking the car and driving 20 minutes every 1-2 days. Battery replacement costs €200-400 at dealers.
Timing chain tensioner wear€1,500 - €2,500
Tensioner loses pressure overnight causing cold start rattle between 80,000-120,000 km · more· less
The B47 is improved over the N47, but timing chain issues still occur, though far less frequently. The tensioner has a release valve that weakens over time, allowing oil pressure to bleed off overnight. This results in a distinctive rattle for 1-30 seconds on cold start. Typically occurs between 80,000-120,000 km. If rattle lasts more than a few seconds, the chain, guides, tensioner, and sprockets all need replacing. B47 timing chain replacement costs €1,785 inc VAT (manual) or €2,145 (automatic) at UK specialists. BMW has updated the tensioner part. The B47 chain is at the front of the engine (unlike N47), making it easier and cheaper to service. Specialists recommend replacement at 90,000 miles or 9 years. Ignoring rattles can lead to chain skip and catastrophic valve/piston contact.
Fuel injector failure€700 - €2,500
Injectors wear or clog after 80,000+ km causing rough idle and misfires · more· less
Approximately 5% of B47 engines experience fuel injector issues within the first 100,000 miles. Diesel injectors can wear out or become clogged over time, especially if low-quality diesel fuel is used. Symptoms include hard starts, rough idling, misfires, poor acceleration, increased fuel consumption, and limp mode. BMW offers two different fuel injectors - one in the €200 range and another over €500. Average replacement cost is €700-900 per injector including labor. The intake manifold must be removed to access injectors, and each injector needs to be coded per cylinder. This is not a DIY job. BMW diesel vehicles have an extended warranty (150,000 km) for injectors and fuel pumps. Use premium diesel and fuel system cleaner to extend injector life.
Turbocharger failure€2,300 - €4,600
Turbo wear from neglected oil changes, typically after 100,000-125,000 km · more· less
Turbocharger problems are described as "fairly common" on BMW diesels. The turbo can fail due to oil contamination, poor-quality oil, or clogged oil lines that starve the turbo of lubrication. Symptoms include loss of power, whining or grinding noise from the turbo, difficulty maintaining high speeds, slower acceleration, grey/blue exhaust smoke, and dashboard warning lights. Dealer quotes for new turbo replacement run €5,000+, while independent mechanics quote around €4,000. Average cost is €2,300-4,600. Turbos usually fail because of insufficient oil changes (BMW's 10,000-12,000 mile intervals are absolute maximum) or blocked breather filters. The average turbocharger runs 100,000-125,000 km. Regular oil changes with high-quality oil are essential. If turbo fails, get it fixed immediately or risk needing a new engine.
Water pump / thermostat failure€700 - €1,400
Mechanical water pump fails between 70,000-100,000 km causing overheating · more· less
The B47 diesel uses a mechanical water pump (unlike electric pumps in petrol BMWs). Failures are common between 70,000-100,000 km. Symptoms include coolant warning light, engine overheating, poor cabin heating, or low coolant levels. The cooling system is a known weak spot on G30 models. Parts cost €250-500 for water pump (Pierburg OEM around €250, genuine BMW over €500), plus €65-110 for thermostat (Mahle €65, BMW €110), and €20-50 for connecting hose. Total repair at independent shop: €700-1,000 (parts €450, labor €500). Dealers charge €1,100-1,400. Replace both water pump and thermostat together (located in same area) to save on labor. Labor is approximately 6 hours due to accessibility.
iDrive infotainment head unit failure€200 - €1,900
Screen goes blank or shows "No Signal", caused by software glitches or head unit failure · more· less
Many G30 owners experience "No Signal" or blank screen problems with iDrive. Dealers confirm this is often related to the head unit itself. Problems can be traced to software glitches (bugs leading to freezing/flickering) or hardware failures (display unit or wiring). BMWs are highly sensitive to voltage changes - a sudden power cut can trigger temporary glitches. First attempt: soft reset by pressing and holding the volume knob for 20-30 seconds until the screen shuts off and restarts. This works for iDrive 6 (found in 2016-2019 G30 models). If that fails, dealers may recommend replacing the entire head unit (€1,900 quote reported). Regular software updates can resolve many glitches. Some cases resolved by replacing one of the main iDrive processors under warranty.
Air suspension failure (if equipped)€800 - €5,000
Rear air suspension leaks or compressor fails on G31 Touring models · more· less
G31 Touring models have rear air suspension as standard (G30 sedan uses conventional springs unless optionally equipped). Common symptoms include car leaning to one side, hissing sounds indicating air leaks, or rear "squatting" down on bump stops while front stays up. You can hear the air compressor kick in but suspension won't lift. Common causes: air release solenoid stuck open (€20 part, 5-minute job), compressor failure, height sensor malfunction, or airbag leaks. Dealer costs: €2,000-2,100 per air spring, €5,000 for airbags and compressor. Independent shops: €800 for complete compressor assembly replacement including connectors. Average suspension repair in UK: £204 (€240). Alternative: coilover conversion kits eliminate faulty air suspension for less than replacing one air strut. The BMW "Power" extended warranty explicitly excludes oil leaks, meaning airbag leaks are not covered.
Oil leaks (valve cover gasket)€350 - €1,600
Valve cover gasket leaks oil, diesel engines require injector removal for access · more· less
Common oil leak areas include valve cover gasket, oil filter housing gasket, and turbo oil lines. Symptoms include oil stains under vehicle, low oil level warning, or smell of burning oil. Valve cover gasket replacement costs €350-800 at independent shops (parts €50-300, labor 2-5 hours at €200-500). Dealer prices: €1,600-2,600+. For B47 diesel engines, the rocker cover gasket replacement requires removing diesel injectors and releasing fuel rail pressure, increasing complexity. It's worth replacing the valve cover itself (plastic, prone to cracking/warping) while injectors are out. Not a DIY job for diesel engines. Common around 80,000-120,000 km.
Solid car but diesel-specific issues require attention
The G30 520d is generally reliable for a premium diesel, but requires proper maintenance. The B47 engine is a significant improvement over the N47, with far fewer timing chain failures. However, like all modern diesels, it suffers from DPF/EGR issues if driven mostly on short trips. Suspension wear is the most common warranty claim on 2017-2023 models. What Car? Reliability Survey shows diesel 5 Series scored 79.8% (last place in executive class), while petrol variants scored 96.7% (third place). Budget for higher maintenance if buying a high-mileage example or one with short-trip driving history.
Pre-Purchase Inspection Checklist
General checks
Service history
Complete BMW dealer or authorized specialist records essential. Verify oil changes every 10,000-12,000 km maximum (shorter intervals better for diesels).
Tires
Standard size 245/45R18. Check tread depth, age (date codes), uneven wear. Run-flats allow 80 km driving after puncture. Rear tires wear faster.
Cold start
Must start engine completely cold. Listen for timing chain rattle in first 30 seconds. Any rattle lasting more than a few seconds indicates chain/tensioner wear.
Test drive
Minimum 30 minutes including highway speeds. Allow engine to reach full operating temperature to check for DPF regeneration issues.
Battery health
Check battery voltage and age. BMW batteries are sensitive. Test Comfort Access and verify no modules staying awake.
Specific for this vehicle
Listen for cold start rattle
Start engine completely cold and listen carefully for timing chain rattle in first 30 seconds. This is the most important check for B47 engines.
Check for DPF warning lights or regeneration issues
Ask owner about DPF regeneration frequency. Cars used for short trips only will have DPF problems. Check for warning lights.
Verify EGR recall completed (2015-2016 production)
Contact BMW with VIN to confirm EGR cooler recall (fire risk) was completed. Check for heat damage to intake manifold.
Test suspension over bumps
Drive over speed bumps and rough roads. Listen for clunking from front control arms/bushings. Check for uneven tire wear.
Check AdBlue system operation
Verify AdBlue level sensor reads correctly, no warning lights. Ask about any previous AdBlue system repairs.
Inspect for oil leaks
Check valve cover, oil filter housing, turbo area. Look underneath for oil stains. Smell for burning oil.
Test iDrive infotainment system
Turn system on/off multiple times. Check for "No Signal" errors or blank screen. Test all functions including navigation.
Check air suspension (G31 Touring)
If Touring model, verify rear air suspension lifts properly, no sagging, no hissing sounds indicating leaks.
Review battery drain history
Ask if car has been driven regularly or sat for long periods. Check if battery has been replaced. Test that all modules enter sleep mode.
Contact a BMW dealer with the VIN to verify all recalls have been completed. The EGR cooler recall is particularly important for 2015-2016 production vehicles. Note that some owners reported additional inlet manifold damage after EGR recall work that BMW dealers claimed was not covered (costing £1,600+). Diesel 5 Series models have shown higher fault rates than petrol variants - 46% took more than a week to fix when problems occurred.
Warranty Status
Factory warranty (2 years unlimited km)Expired on 2017-2021 models
Extended warranty availableBMW Service Inclusive packages
Diesel injector/fuel pump warranty150,000 km in some markets
AdBlue system warranty (USA)10 years (EU varies by country)
Most 2017-2021 G30 520d models are outside their original factory warranty. BMW offers extended warranty packages, but carefully review exclusions - oil leaks and some suspension components are often not covered. In the USA, AdBlue systems have a 10-year warranty; European owners should check local BMW for comparable coverage, as AdBlue sensor failures are common. Consider purchasing extended warranty if buying a higher-mileage example (100,000+ km).
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.