Deep metallic engine knock: which faults cause it?

The most important among the documented faults: oil-bath timing belt degradation, in the 1.2 PureTech; rear timing chain stretch and breakage, in the BMW N47; timing chain stretch and tensioner failure, in the OM651 and the 1.3 Multijet; intake swirl flap breakage (swirl flaps), in the BMW M47; timing chain stretch, in the 2.0 Ingenium diésel; wear and seizure of the big-end bearings, in the 1.5 dCi; excessive oil consumption and engine failure, in the 1.2 TCe; MHSG belt tensioner and crankshaft pulley failure (48V mild hybrid), in the 1.6 CRDi.

NoisesUrgency: As soon as possible

Deep metallic engine knock: causes and the faults that trigger it

37 documented faults cause it in 34 engines. The most important:

Critical severity: Oil-bath timing belt degradation · 1.2 PureTech
Critical severity: Rear timing chain stretch and breakage · BMW N47
Critical severity: Timing chain stretch and tensioner failure · OM651 and 1.3 Multijet

What to do now

As soon as possible

Switch the engine off and do not drive on. Carrying on can snap a connecting rod and leave the engine beyond repair.

What it means

A deep knock that gets louder with engine speed usually points to internal damage, such as big-end bearings worn through lack of lubrication. It is one of the most serious faults an engine can have.

General explanation from MotorFiable. How it shows up in each engine, with sources, is in the list of faults.

Reviewed on 9 October 202651 sources How we work

Faults that cause it

Specific engine and gearbox faults, from most to least important (severity × frequency). Below each title, how the symptom shows up in that fault.

- Critical severityVery frequentFrequency: Very frequent1.2 PureTechOil-bath timing belt degradationAbnormal metallic noises from the engine.Repair (garage): €400–€800
Source for the symptom in the 1.2 PureTech^[1]
- Critical severityVery frequentFrequency: Very frequentBMW N47Rear timing chain stretch and breakageIf the breakage has damaged pistons or valves, a serious internal knocking appears, which makes it inadvisable to keep driving.Repair (garage): €1,590–€3,000Appears at around 50,000 km
Source for the symptom in the BMW N47^[2]
- Critical severityVery frequentFrequency: Very frequentOM651Timing chain stretch and tensioner failureIn the worst cases, if the chain jumps or comes off, there is internal knocking and major engine damage.Repair (garage): €2,000–€3,500Appears at around 120,000 km
Source for the symptom in the OM651^[3][4]
- Critical severityVery frequentFrequency: Very frequentBMW M47Intake swirl flap breakage (swirl flaps)If the remains of a broken flap enter the cylinder, a serious internal knocking noise may appear, which makes it inadvisable to keep driving.
Source for the symptom in the BMW M47^[5]
- Critical severityVery frequentFrequency: Very frequent2.0 Ingenium diéselTiming chain stretchIn the most serious cases, if the chain jumps teeth, internal knocking and damage to pistons or valves appear, forcing an engine replacement.Repair (garage): €4,000–€7,000Appears at around 90,000 km
Source for the symptom in the 2.0 Ingenium diésel^[6][7]
- Critical severityCommonFrequency: Common1.5 dCiWear and seizure of the big-end bearingsA dull knocking that follows the engine speed and gets worse when hot; according to fiches-auto, it indicates that failure is near.
Source for the symptom in the 1.5 dCi^[8]
- Critical severityCommonFrequency: Common1.2 TCeExcessive oil consumption and engine failureAbnormal engine noises in the most advanced cases.Repair: €5,000–€10,000
Source for the symptom in the 1.2 TCe^[9][10][11]
- Critical severityCommonFrequency: Common1.3 MultijetTiming chain stretch and tensioner failureA deeper knocking noise may indicate that the lack of oil pressure has already worn the bearings or camshaft.Repair (garage): €350–€550Appears at around 70,000 km
Source for the symptom in the 1.3 Multijet^[12]
- Critical severityCommonFrequency: Common1.6 CRDiMHSG belt tensioner and crankshaft pulley failure (48V mild hybrid)Internal noises and loss of performance if the crankshaft and camshafts have already lost synchronisation.
Source for the symptom in the 1.6 CRDi^[13]
- Critical severityCommonFrequency: CommonBMW N43/N46Wear and breakage of the timing chain guidesIf a guide breaks, its fragments can block the oil pump strainer and leave the engine without lubrication, with the resulting risk of seizure.
Source for the symptom in the BMW N43/N46^[14]
- Critical severityCommonFrequency: CommonMZR-CDTiming chain stretch on the 2.2 MZR-CDIf the noise is ignored, the chain can jump teeth or break and damage the engine internally.
Source for the symptom in the MZR-CD^[15]
- Critical severityCommonFrequency: CommonM271Timing chain stretch and wear of the camshaft sprocketsIf the chain jumps teeth, serious internal engine damage can result.
Source for the symptom in the M271^[16]
- Critical severityCommonFrequency: Common1.9 dCiSeizure and wear of the big-end bearingsA dull metallic knocking that follows engine speed and worsens when hot usually precedes the failure.
Source for the symptom in the 1.9 dCi^[17]
- Critical severityCommonFrequency: Common1.9 TDIBig-end bearing failureA heavy metallic knock from the engine block usually precedes the bearing failure, according to the catastrophic failure cases recorded in several models.Appears at around 138,000 km
Source for the symptom in the 1.9 TDI^[18][19]
- High severityVery frequentFrequency: Very frequent1.2 PureTechExcessive oil consumption from carbon on the piston rings or oil separator failureKnocking or pre-ignition from carbon built up in the combustion chamber.
Source for the symptom in the 1.2 PureTech^[20][21]
- High severityCommonFrequency: Common2.0 Ingenium diéselBalance shaft bearing wearIn the most advanced cases, the wear can lead to major engine damage if it is not corrected in time.
Source for the symptom in the 2.0 Ingenium diésel^[22]
- Critical severityOccasionalFrequency: Occasional1.6 / 2.2 i-DTECDiesel injector wear or failureMetallic knocking that varies with acceleration, described by several owners as an injector noise.Appears at around 70,000 km
Source for the symptom in the 1.6 / 2.2 i-DTEC^[23]
- Critical severityOccasionalFrequency: Occasional1.6 GDI / T-GDILow-speed pre-ignition and connecting rod damage in the 1.6 T-GDI (documented in the US)A metallic knock or rattle that worsens with engine speed, described by several owners as 'rod knock'.Appears at around 100,000 km
Source for the symptom in the 1.6 GDI / T-GDI^[24][25][26]
- Critical severityOccasionalFrequency: Occasional2.0 / 2.4 GDI and T-GDI (Theta II)Premature connecting rod bearing wearAbnormal knocking noises from the engine: one of the two symptoms the German press cites when explaining Kia's campaign.
Source for the symptom in the 2.0 / 2.4 GDI and T-GDI (Theta II)^[27]
- Critical severityOccasionalFrequency: OccasionalTDV6 / SDV6Crankshaft breakage and spinning main bearing shellsA deep knock or rumble from the bottom of the engine, worse under load and when cold.
Source for the symptom in the TDV6 / SDV6^[28][29]
- Critical severityOccasionalFrequency: OccasionalSkyactiv-DOil pump chain breakage and camshaft wearA metallic knock that increases with revs can indicate that the camshaft or bearings are already damaged by lack of lubrication.
Source for the symptom in the Skyactiv-D^[30]
- Critical severityOccasionalFrequency: OccasionalM270/M274Camshaft breakage due to a defective weld (2015 units)In the most serious cases, the camshaft breaking causes internal damage and abnormal engine noises.
Source for the symptom in the M270/M274^[31][32]
- Critical severityOccasionalFrequency: OccasionalPorsche V8 and V6 (Cayenne and Panamera)Cylinder bore scoring in the Cayenne 4.5 V8 blockPiston noise or slap; Car Mechanics advises paying attention to engine knocking on the 955 V8 engines.
Source for the symptom in the Porsche V8 and V6 (Cayenne and Panamera)^[33][34]
- Critical severityOccasionalFrequency: Occasional2.0 dCiTiming chain wear or breakageIn the most advanced cases, serious knocking if the chain has jumped teeth and the valves have hit the pistons.
Source for the symptom in the 2.0 dCi^[35]
- Critical severityOccasionalFrequency: Occasional3.0 TDI V6Camshaft breakage on the EA897 evo (CRT and CZV)Knocking or ticking noises clearly louder than the normal ones of a diesel; a specialist must tell them apart from chain rattle.
Source for the symptom in the 3.0 TDI V6^[36]
- Medium severityVery frequentFrequency: Very frequent2.0 HDiPremature dual-mass flywheel wear (from 107/110 hp)Knocking or a metallic noise that changes with the revs.
Source for the symptom in the 2.0 HDi^[37]
- High severityOccasionalFrequency: Occasional2.2 i-CTDiDiesel injector failure or wearA metallic knocking that varies with acceleration is one of the symptoms owners describe when the final diagnosis is an injector.Appears at around 86,000 km
Source for the symptom in the 2.2 i-CTDi^[38]
- High severityOccasionalFrequency: OccasionalM112 / M113Crankshaft pulley (vibration damper) failureRattling or metallic knocking in the engine bay, which usually signals that the pulley is loose or damaged.
Source for the symptom in the M112 / M113^[39][40]
- High severityOccasionalFrequency: Occasional2.5 TDI R5Camshaft and hydraulic tappet wearKnocking noise from the top of the engine and rough idle from cam and follower wear.
Source for the symptom in the 2.5 TDI R5^[41]
- Critical severityRareFrequency: Rare1.6 GDI / T-GDIPiston and connecting rod damage from catalytic converter overheating in the naturally aspirated 1.6 GDIA knock if the damage already affects the piston or connecting rod.
Source for the symptom in the 1.6 GDI / T-GDI^[42]
- Medium severityOccasionalFrequency: Occasional1.6 DIG-TTiming chain wear and noiseA knocking or rattling that increases with revs in the most advanced cases.
Source for the symptom in the 1.6 DIG-T^[43]
- Medium severityOccasionalFrequency: Occasional2.0 16v F4R and F4RTFaulty camshaft variable valve timing pulleyDiesel-like metallic rattle at idle or when warm, sometimes with no fault code stored.
Source for the symptom in the 2.0 16v F4R and F4RT^[44][45]
- Medium severityOccasionalFrequency: OccasionalSubaru bóxerImprecise injectors and sooty EGR valve on the EE20 dieselKnocking noises, like "pinking", from injectors working imprecisely, according to AUTO BILD.
Source for the symptom in the Subaru bóxer^[46]
- High severityRareFrequency: RareOM656Faulty roller rocker arms and Camtronic solenoid valve failuresUneven idle and clicking noises while driving when the camshaft is worn, according to MBpassion.
Source for the symptom in the OM656^[47]
- High severityRareFrequency: Rare1.8/2.2 DI-DBalance shaft failure on the Outlander's 2.2 DI-DEngine knocking is the symptom the source we consulted records for these cases.
Source for the symptom in the 1.8/2.2 DI-D^[48]
- Medium severityRareFrequency: Rare2.2 HDiDual-mass flywheel wear, less frequent than on other HDi enginesKnocking or metallic noise that changes with revs.
Source for the symptom in the 2.2 HDi^[49]
- Low severityOccasionalFrequency: OccasionalBMW N52 / N53N52 hydraulic lifter noiseClicking or rattling, especially when cold.
Source for the symptom in the BMW N52 / N53^[50][51]

Which cars it appears in

These faults affect 34 engines. We have documented 229 models from 31 makes with some of the affected versions: open yours to see all its faults.

Engines

Cars with the affected versions

Alfa Romeo

Alfa Romeo MiToEngine: 1.3 MultijetYears: 2008–2018

Audi

BMW

See all BMW models

Citroën

See all Citroën models

Dacia

DS

Fiat

Ford

Honda

Hyundai

Infiniti

Infiniti Q30Engine: OM651Years: 2015–2019

Jaguar

Jeep

Jeep AvengerEngine: 1.2 PureTechYears: since 2023

Kia

Lancia

Lancia Ypsilon IIIEngine: 1.3 MultijetYears: 2011–2024

Land Rover

Mazda

Mercedes-Benz

See all Mercedes-Benz models

MINI

Mitsubishi

Nissan

Seat

Škoda

Subaru

Suzuki

Toyota

Toyota ProAce CityEngine: 1.2 PureTechYears: 2019–2025

Volkswagen

Volvo

Engine knock: causes in your car

85 cars have several documented faults that cause this symptom. Choose yours to see only those that affect it, by engine and by year.

BMW 6

Citroën 13

Dacia 1

Dacia Duster I

DS 4

Honda 1

Honda CR-V III

Hyundai 5

Jaguar 3

Jeep 1

Jeep Avenger

Kia 4

Mercedes-Benz 12

Nissan 4

Opel 5

Peugeot 16

Renault 9

Toyota 1

Toyota ProAce City

Engine knock by brand

Fault codes that may go with it

If you have an OBD reader, the code stored by the control unit helps you work out which system is failing.

Other symptoms: noises

All symptoms

Has this happened to you? Tell us which fault it was, at how many kilometres and how much you paid: it helps other owners know what to expect. Report your fault.

Sources

Every fact on this page links to its source. If you find an error, let us know.

1.1.2 PureTech: precio y cambio de correa de distribuciónAutopista · Motoring press · published 2 August 2026 · consulted 26 September 2026 · in Spanish
2.Las graves (y costosas) averías que puede causar en tu coche la rotura de la cadena de distribuciónDiariomotor · Motoring press · consulted 26 September 2026 · in Spanish
3.Mercedes-Rückruf: Wieder Probleme mit dem OM651-DieselmotorAutoservicepraxis · Motoring press · published 12 January 2015 · consulted 26 September 2026 · in German
4.Mercedes OM651: Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 26 September 2026 · in German
5.BMW M47Wikipedia (inglés) · Other source · consulted 27 September 2026
6.Fiabilité Jaguar XE, pannes et témoignagesFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
7.Fiabilité Jaguar F-Pace, pannes et témoignagesFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
8.Bruit de cliquetis - claquement : les causesFiches-auto.fr · Motoring press · published 6 November 2025 · consulted 26 September 2026 · in French
9.Moteur 1.2 Renault - 400 000 voitures en dangerUFC-Que Choisir (Que Choisir Ensemble) · Consumer association · published 24 May 2019 · consulted 26 September 2026 · in French
10.Problème moteur Renault-Dacia 1.2 TCe, Nissan 1.2 DIG-T et Mercedes - Vos questions, nos réponsesUFC-Que Choisir (Que Choisir Ensemble) · Consumer association · published 24 May 2019 · consulted 26 September 2026 · in French
11.Renault 1.2 TCe et Nissan 1.2 DIG-T : des moteurs gourmands en huileL'argus · Motoring press · published 12 October 2016 · consulted 26 September 2026 · in French
12.Fiat 1.3 JTD/Multijet: corrente folgada e entupimento dos canais de lubrificaçãoProvmec · Technical documentation · consulted 26 September 2026 · in Portuguese
13.Kia / Hyundai 1.6 CRDi MHEV Engine FailuresDOHC (especialista en reconstrucción de motores) · Technical documentation · consulted 26 September 2026
14.BMW N43Wikipedia (inglés) · Other source · consulted 27 September 2026
15.Mazda 6 II: Bekannte Probleme und Schwachstellengebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German
16.Mercedes M271: Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
17.Renault Mégane II (2002 – 2009): Probleme & SchwachstellenGebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German
18.Tous les problèmes sur Volkswagen Golf Vfiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
19.Tous les problèmes sur Škoda Octavia (1997-2004)fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
20.Fiabilité du 1.2 PuretechFiches-auto.fr · Motoring press · consulted 26 September 2026 · in French
21.Moteur 1.2 PureTech Stellantis. Changement d'huile pour le trois-cylindres essenceL'argus · Motoring press · published 13 February 2024 · consulted 26 September 2026 · in French
22.Jaguar Land Rover's Four-Cylinder Ingenium Engine Is Still Giving Its Maker HeadachesAOL · Motoring press · published 10 August 2026 · consulted 27 September 2026
23.Fiabilité et pannes Honda Civic (2012-2017)Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
24.Complaints by vehicle: Hyundai Veloster, model year 2013NHTSA · Official body · consulted 27 September 2026
25.Complaints by vehicle: Hyundai Tucson, model year 2016NHTSA · Official body · consulted 27 September 2026
26.Hyundai Veloster problemsCarComplaints.com · Owners' forum · consulted 27 September 2026
27.Kia-Rückruf: Pleuellager zu schwachauto motor und sport · Motoring press · published 29 September 2023 · consulted 8 October 2026 · in German
28.Land Rover Discovery TDV6 engine failures making headlinesLandyOnline · Other source · published October 2015 · consulted 5 October 2026
29.Land Rover & Jaguar SDV6/TDV6 Crankshaft RepairJLR Engines · Technical documentation · consulted 5 October 2026
30.Fiabilité Mazda 6 (2012-2022)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
31.Mercedes M274: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
32.Mercedes M270: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
33.Alusil (aleación de aluminio y silicio para cilindros)Wikipedia (inglés) · Other source · consulted 9 October 2026
34.Buying, owning, improving the Porsche Cayenne 958Car Mechanics · Motoring press · published 24 September 2025 · consulted 9 October 2026
35.Fiabilité Renault Espace 4 : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
36.Informationen zu den Audi Nockenwellen Problemen am 3.0 TDI (CRT & CZV) Motor im A4, A5, A6, A7 sowie dem Q5 & Q7CarWiki.de · Other source · consulted 9 October 2026 · in German
37.Fiabilité du 2.0 HDIFiches-Auto · Motoring press · consulted 27 September 2026 · in French
38.Fiabilité et pannes Honda Civic (2006-2011)Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
39.Mercedes M-Klasse W163: Typische Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · published 4 June 2023 · consulted 8 October 2026 · in German
40.Mercedes E-Klasse W211, S211: Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · published 12 February 2024 · consulted 8 October 2026 · in German
41.Common VW 2.5 TDI PD Problems & IssuesTorque Cars · Technical documentation · consulted 5 October 2026
42.Recall 19V120000 - Kia Soul (catalytic converter overheating / piston and rod damage)NHTSA · Official body · published 2019 · consulted 27 September 2026
43.Avis moteur Nissan Qashqai 2 1.6 163 chFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
44.Fiabilité occasion Renault Mégane II (2002-2009)CarVerif · Other source · consulted 5 October 2026 · in French
45.Mégane II distribution poulie déphasagePlanète Renault (foro) · Owners' forum · consulted 5 October 2026 · in French
46.Subaru XV I im Gebrauchtwagen-Test: «Vorsicht vor dem Boxer-Diesel!»AUTO BILD · Motoring press · published 17 December 2019 · consulted 9 October 2026 · in German
47.Mercedes OM656 Diesel: Häufige Probleme, Ursachen & Tipps zur Vermeidung von MotorschädenMBpassion · Motoring press · published 19 February 2026 · consulted 9 October 2026 · in German
48.Mitsubishi Outlander: bekannte Probleme und MängelGebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German
49.Essai, avis et fiabilité des 2,2 HDI 136 chevauxFiches-Auto · Motoring press · consulted 27 September 2026 · in French
50.BMW N52 Engine ProblemsBMW Tuning · Other source · consulted 5 October 2026
51.These BMW N52 Years Have The Most ProblemsJalopnik · General press · consulted 5 October 2026