Mercedes-Benz CLA C118

Renault-based small diesel, new generation. Economical with SCR catalyst, but still with little power reserve. Automatic only.

• !! Timing belt maintenance obligation from 120,000 km

  Like its Renault counterpart, the OM608 uses a timing belt. Prescribed change every 120,000 km or 6 years -- frequently forgotten as Mercedes buyers are accustomed to timing chains.

  Symptoms: No warning on snap -- sudden engine failure and severe engine damage
  600–1,200 $
  Ad timing belt OM608timing belt kit OM608 1.5 dCi
• !! Timing belt change critical from 120,000 km

  The OM608 (Renault K9K base) uses a timing belt. Mercedes specifies 200,000 km change interval; Renault prescribes 120,000 km for the same engine. A snap causes immediate total damage on this interference engine.

  Symptoms: No noticeable warning before snap; beforehand: faint squealing, occasionally starting difficulties
  450–850 $
  Ad timing belt kit OM607 OM608timing belt kit K9K
• !! Increased oil consumption / turbo shaft seal from 100,000 km

  The Renault-based OM608 1.5 CDI sometimes shows increased oil consumption from early on due to a leaking turbocharger shaft seal. Oil mist in the intake tract behind the turbo.

  Symptoms: Dropping oil level, oil mist or blue smoke from exhaust, oil in air filter housing behind turbo
  800–2,000 $
  Ad turbocharger gasket OM608Turbogasket OM608turbocharger OM608

+ 2 more engine weaknesses + vehicle weaknesses

Completely new aluminium diesel with NANOSLIDE coating and integrated particulate filter. Noticeably quieter and cleaner than the OM651. Few typical faults known to date.

• !! Rocker Arm and Camshaft Wear from 80,000 km

  Known weak point: the narrow camshaft lobes and rocker arms in the OM654 wear prematurely due to inadequate lubrication. Mercedes issued TSBs.

  Symptoms: Ticking or knocking from engine bay, misfires, rough running, engine warning light
  2,000–5,000 $
  Ad OM654 rocker armOM654 camshaft VerschleißMercedes OM654 valvetrieb
• !! Electric Coolant Pump Leaking — Recall

  Over 800,000 Mercedes diesel vehicles with OM654/OM656 were recalled due to a leaking electric coolant pump. Coolant loss can lead to overheating.

  Symptoms: Coolant loss, overheating warning, coolant warning light, engine temperature rises
  0–500 $
  Ad OM654 coolant pumpcoolant pump OM654 recallA0005001400
• !! NOx Sensor Defective — AdBlue Fault and Start Inhibit from 90,000 km

  NOx sensors wear out from soot particles and deliver erroneous readings. Consequence: incorrect AdBlue injection, CEL illumination; if unaddressed, an engine start inhibit may follow. Both sensors can be affected.

  Symptoms: CEL, AdBlue warning, fault code P20EE or P204F, message 'No start after X km', rough idle
  500–2,000 $
  Ad NOx sensor A0009050108NOx sensor A0009050208Lambda sensor SCR Mercedes OM654

+ 8 more engine weaknesses + vehicle weaknesses

Completely new aluminium diesel with NANOSLIDE coating and integrated particulate filter. Noticeably quieter and cleaner than the OM651. Few typical faults known to date.

• !! Rocker Arm and Camshaft Wear from 80,000 km

  Known weak point: the narrow camshaft lobes and rocker arms in the OM654 wear prematurely due to inadequate lubrication. Mercedes issued TSBs.

  Symptoms: Ticking or knocking from engine bay, misfires, rough running, engine warning light
  2,000–5,000 $
  Ad OM654 rocker armOM654 camshaft VerschleißMercedes OM654 valvetrieb
• !! Electric Coolant Pump Leaking — Recall

  Over 800,000 Mercedes diesel vehicles with OM654/OM656 were recalled due to a leaking electric coolant pump. Coolant loss can lead to overheating.

  Symptoms: Coolant loss, overheating warning, coolant warning light, engine temperature rises
  0–500 $
  Ad OM654 coolant pumpcoolant pump OM654 recallA0005001400
• !! NOx Sensor Defective — AdBlue Fault and Start Inhibit from 90,000 km

  NOx sensors wear out from soot particles and deliver erroneous readings. Consequence: incorrect AdBlue injection, CEL illumination; if unaddressed, an engine start inhibit may follow. Both sensors can be affected.

  Symptoms: CEL, AdBlue warning, fault code P20EE or P204F, message 'No start after X km', rough idle
  500–2,000 $
  Ad NOx sensor A0009050108NOx sensor A0009050208Lambda sensor SCR Mercedes OM654

+ 8 more engine weaknesses + vehicle weaknesses

AMG version of the M260 with 306 hp. 7G-DCT and 4MATIC standard. Independent tuning with reinforced bottom end. Good balance of everyday usability and performance.

• !! Cylinder Head Exhaust Valves Worn from 35,000 km

  Same production defect as in the standard M260: exhaust valve seat inserts wear prematurely causing engine misfires. Mercedes extended warranty to 15 years.

  Symptoms: Heavy vibration, misfires (MIL with misfire faults P030x), noticeable power loss
  4,000–8,000 $
  Ad Cylinder head M260-AMG35Cylinder head M260 AMGA2600101905
• !! Valve Seat Insert Wears — Cylinder Head Damage from 50,000 km

  Known production issue on early M260 engines: exhaust valve seat inserts wear prematurely. Mercedes Canada extended warranty to 15 years/241,000 km.

  Symptoms: Misfires, rough running, power loss, compression test shows drop, MIL illuminated
  3,500–6,000 $
  Ad Cylinder head M260-AMG35Cylinder head M260 AMGValve seat insert M260-AMG35
• !! Turbocharger Wear Under AMG Load from 90,000 km

  The higher-boosted M260 shows premature turbocharger wear with spirited driving. Inadequate cool-down periods accelerate bearing damage.

  Symptoms: Whistling from turbo, power drop at high rpm, oil mist in intake tract
  1,500–3,500 $
  Ad Turbocharger M260-AMG35Turbocharger M260 AMGTurbo M260-AMG35

+ 2 more engine weaknesses + vehicle weaknesses

The M139 is the logical development of the M133 and surpasses it in every respect: more power, better thermal management through an improved cooling concept, combined direct and port injection to fight intake valve carbon build-up. As a young engine with limited long-term data it is considered robust so far. Isolated reports of coolant sensor issues and water pump failures at high speeds. Tuning potential is enormous, but fuel supply must be upgraded at higher power levels.

• !! Turbocharger Stress Under Extreme Use from 100,000 km

  The world's most powerful series-production four-cylinder at 421 hp subjects its turbocharger to extreme stress. Without adequate cool-down periods after full-load operation, premature bearing wear is likely.

  Symptoms: Whistling at high load, oil mist in intake tract, power drop in heat
  2,500–5,000 $
  Ad Turbocharger M139Turbocharger M139 AMGTurbo M139 replacement
• !! Turbocharger Shaft Seal Leaking from 80,000 km

  The high-performance turbocharger on the M139 can push oil into the intake tract due to excessive shaft play. Early vehicles were subject to a recall for turbocharger bearing defects.

  Symptoms: Oil consumption without visible leaks, smoke cloud on cold start, power drop under high load
  2,000–5,000 $
  Ad Turbocharger M139BorgWarner turbocharger M139Turbo M139 BorgWarner
• !! Overheating After Spirited Driving from 60,000 km

  The M139 cooling system is designed at its limits. After extended high-load phases coolant temperature can reach critical values, especially in warm weather.

  Symptoms: Coolant temperature warning after spirited driving, restricted engine power through thermal management
  800–2,500 $
  Ad Water pump M139Cooling M139 AMGA1332001900 thermostat M139

+ 3 more engine weaknesses + vehicle weaknesses

The M139 is the logical development of the M133 and surpasses it in every respect: more power, better thermal management through an improved cooling concept, combined direct and port injection to fight intake valve carbon build-up. As a young engine with limited long-term data it is considered robust so far. Isolated reports of coolant sensor issues and water pump failures at high speeds. Tuning potential is enormous, but fuel supply must be upgraded at higher power levels.

• !! Turbocharger Stress Under Extreme Use from 100,000 km

  The world's most powerful series-production four-cylinder at 421 hp subjects its turbocharger to extreme stress. Without adequate cool-down periods after full-load operation, premature bearing wear is likely.

  Symptoms: Whistling at high load, oil mist in intake tract, power drop in heat
  2,500–5,000 $
  Ad Turbocharger M139Turbocharger M139 AMGTurbo M139 replacement
• !! Turbocharger Shaft Seal Leaking from 80,000 km

  The high-performance turbocharger on the M139 can push oil into the intake tract due to excessive shaft play. Early vehicles were subject to a recall for turbocharger bearing defects.

  Symptoms: Oil consumption without visible leaks, smoke cloud on cold start, power drop under high load
  2,000–5,000 $
  Ad Turbocharger M139BorgWarner turbocharger M139Turbo M139 BorgWarner
• !! Overheating After Spirited Driving from 60,000 km

  The M139 cooling system is designed at its limits. After extended high-load phases coolant temperature can reach critical values, especially in warm weather.

  Symptoms: Coolant temperature warning after spirited driving, restricted engine power through thermal management
  800–2,500 $
  Ad Water pump M139Cooling M139 AMGA1332001900 thermostat M139

+ 3 more engine weaknesses + vehicle weaknesses

Joint development with Renault (H5Ht). Cylinder bore coating: NANOSLIDE. Compact and economical, but somewhat strained under high load. Also used as PHEV base (250e).

• !! Increased oil consumption from 60,000 km

  Some M282 engines show early increased oil consumption from defective piston rings and oil scraper rings. The problem sometimes appears at low mileages.

  Symptoms: Dropping oil level between service visits, occasionally slight blue smoke when accelerating
  1,500–4,000 $
  Ad piston rings M282piston ringsatz M282M282 oil consumption
• !! Increased oil consumption from piston ring wear from 60,000 km

  Some M282 engines show progressive oil consumption from low mileage. Cause: defective oil rings or pistons. Direct injection washes oil off the cylinder wall.

  Symptoms: Regular oil top-ups required, no visible leaks, no smoke from exhaust
  2,000–5,000 $
  Ad piston ringsatz M282M282.914 piston ringsA2820300017
• !! Boost pressure loss from turbo or charge air hose from 120,000 km

  The M282 turbocharger can lose power at higher mileage from bearing wear or leaking charge air pipes. The wastegate actuator can deliver incorrect signals.

  Symptoms: Power drop at full throttle, whistling in the engine bay, boost pressure too low warning (P0299)
  1,200–3,500 $
  Ad turbocharger M282turbocharger M282.914A2820900280

+ 2 more engine weaknesses + vehicle weaknesses

Joint development with Renault (H5Ht). Cylinder bore coating: NANOSLIDE. Compact and economical, but somewhat strained under high load. Also used as PHEV base (250e).

• !! Increased oil consumption from 60,000 km

  Some M282 engines show early increased oil consumption from defective piston rings and oil scraper rings. The problem sometimes appears at low mileages.

  Symptoms: Dropping oil level between service visits, occasionally slight blue smoke when accelerating
  1,500–4,000 $
  Ad piston rings M282piston ringsatz M282M282 oil consumption
• !! Increased oil consumption from piston ring wear from 60,000 km

  Some M282 engines show progressive oil consumption from low mileage. Cause: defective oil rings or pistons. Direct injection washes oil off the cylinder wall.

  Symptoms: Regular oil top-ups required, no visible leaks, no smoke from exhaust
  2,000–5,000 $
  Ad piston ringsatz M282M282.914 piston ringsA2820300017
• !! Boost pressure loss from turbo or charge air hose from 120,000 km

  The M282 turbocharger can lose power at higher mileage from bearing wear or leaking charge air pipes. The wastegate actuator can deliver incorrect signals.

  Symptoms: Power drop at full throttle, whistling in the engine bay, boost pressure too low warning (P0299)
  1,200–3,500 $
  Ad turbocharger M282turbocharger M282.914A2820900280

+ 2 more engine weaknesses + vehicle weaknesses

Powerful two-litre turbo from the new compact platform. 7G-DCT or 8G-DCT standard. Strong everyday engine with few known weaknesses.

• !! Exhaust Valve Seat Insert Wear / Cylinder Head from 40,000 km

  Known production deficiency: exhaust valve seat inserts and valve guides wear prematurely, leading to leaking combustion chambers. Mercedes extended warranty to 15 years / 241,000 km for model years 2019–2022.

  Symptoms: Rough engine running, misfires (faults P0300–P0304), check engine light, power loss, vibration
  3,000–8,000 $
  Ad Cylinder head M260A2600101905Cylinder head M260 2.0
• !! Timing Chain Rattles on Cold Start from 90,000 km

  On the M260 timing chain and tensioner can wear prematurely, especially with long oil change intervals. Affected vehicles show rattling on cold start.

  Symptoms: Metallic rattling after cold start, check engine light, camshaft position fault codes
  1,500–3,600 $
  Ad Timing chain kit M260Chain tensioner M260A2740520016 timing chain
• !! Wastegate Actuator Causes Boost Pressure Loss from 100,000 km

  The wastegate actuator on the M260 can open prematurely from spring wear, leading to underboost. Diagnosis possible by pressure-testing the actuator.

  Symptoms: Power deficiency under load, P0299 fault code, whistling on acceleration
  500–1,800 $
  Ad wastegate actuator M260A2740900180 wastegate M260

+ 2 more engine weaknesses + vehicle weaknesses

Powerful two-litre turbo from the new compact platform. 7G-DCT or 8G-DCT standard. Strong everyday engine with few known weaknesses.

• !! Exhaust Valve Seat Insert Wear / Cylinder Head from 40,000 km

  Known production deficiency: exhaust valve seat inserts and valve guides wear prematurely, leading to leaking combustion chambers. Mercedes extended warranty to 15 years / 241,000 km for model years 2019–2022.

  Symptoms: Rough engine running, misfires (faults P0300–P0304), check engine light, power loss, vibration
  3,000–8,000 $
  Ad Cylinder head M260A2600101905Cylinder head M260 2.0
• !! Timing Chain Rattles on Cold Start from 90,000 km

  On the M260 timing chain and tensioner can wear prematurely, especially with long oil change intervals. Affected vehicles show rattling on cold start.

  Symptoms: Metallic rattling after cold start, check engine light, camshaft position fault codes
  1,500–3,600 $
  Ad Timing chain kit M260Chain tensioner M260A2740520016 timing chain
• !! Wastegate Actuator Causes Boost Pressure Loss from 100,000 km

  The wastegate actuator on the M260 can open prematurely from spring wear, leading to underboost. Diagnosis possible by pressure-testing the actuator.

  Symptoms: Power deficiency under load, P0299 fault code, whistling on acceleration
  500–1,800 $
  Ad wastegate actuator M260A2740900180 wastegate M260

+ 2 more engine weaknesses + vehicle weaknesses

Joint development with Renault (H5Ht). Cylinder bore coating: NANOSLIDE. Compact and economical, but somewhat strained under high load. Also used as PHEV base (250e).

• !! Increased oil consumption from 60,000 km

  Some M282 engines show early increased oil consumption from defective piston rings and oil scraper rings. The problem sometimes appears at low mileages.

  Symptoms: Dropping oil level between service visits, occasionally slight blue smoke when accelerating
  1,500–4,000 $
  Ad piston rings M282piston ringsatz M282M282 oil consumption
• !! Increased oil consumption from piston ring wear from 60,000 km

  Some M282 engines show progressive oil consumption from low mileage. Cause: defective oil rings or pistons. Direct injection washes oil off the cylinder wall.

  Symptoms: Regular oil top-ups required, no visible leaks, no smoke from exhaust
  2,000–5,000 $
  Ad piston ringsatz M282M282.914 piston ringsA2820300017
• !! Boost pressure loss from turbo or charge air hose from 120,000 km

  The M282 turbocharger can lose power at higher mileage from bearing wear or leaking charge air pipes. The wastegate actuator can deliver incorrect signals.

  Symptoms: Power drop at full throttle, whistling in the engine bay, boost pressure too low warning (P0299)
  1,200–3,500 $
  Ad turbocharger M282turbocharger M282.914A2820900280

+ 2 more engine weaknesses + vehicle weaknesses