Is the Mercedes‑AMG GT R / GT R Pro engine reliable?

The M178 is a masterpiece of engineering, hand‑built by AMG in Affalterbach. The powertrain is generally considered 'solid', but it has well‑documented issues: stuck injectors and misfire codes, dynamic engine/transmission mount failures, oil leaks, faulty exhaust flaps, catalytic converter failure, and complex battery/electrical issues. Regular maintenance is absolutely essential.

What are the common problems with the Mercedes‑AMG GT R / GT R Pro?

Fuel injector sticking and misfire codes (the most critical engine issue), dynamic engine and transmission mount failure, oil leaks (transmission case and dry sump), exhaust flap and catalytic converter failure, and battery/electrical system issues. Both the GT R and GT R Pro share the same engine and thus the same problems. See the Era Map above for detailed advice.

Is it worth replacing a Mercedes‑AMG GT R / GT R Pro engine, or should I scrap the car?

Depends on vehicle value. Against a well‑kept GT R (values £70,000–£120,000+ depending on condition and mileage), a £8,000–£10,000 reconditioned engine is 8–15% of the vehicle's value — worth it. The GT R Pro, with its limited production, commands even higher values. Given the GT R's status as a future classic and rising values, engine replacement is almost always worth it for a solid example.

How do I find my Mercedes‑AMG GT R / GT R Pro engine code?

The engine code M178 is listed on the VIN plate and vehicle documentation. Both the GT R (2017–2021) and GT R Pro (2019–2021) use the same 4.0‑litre M178 V8 biturbo engine producing 577 bhp (585 PS). The engine is hand‑crafted by AMG in Affalterbach. Tell us your registration and we'll confirm for free.

Can I repair the M178 injectors, or does it require engine replacement?

Injector sticking and misfire issues are always repairable without replacing the engine — if caught early. Injector replacement costs £500–£1,500, and the ME control unit software should be updated to version VC 5.1 or later. However, if a misfire is left unaddressed, it can destroy the catalytic converters, leading to bills of £2,000–£5,000+ and parts on back order for months. At the first sign of rough running or a CEL, book an inspection immediately.

Mercedes‑AMG GT R / GT R Pro2017–2021M178 4.0 V8 Biturbo

Mercedes‑AMG GT R / GT R Pro Engine Replacement — Compare Prices & Get Quotes

Name: Mercedes‑AMG GT R / GT R Pro UK Engine Enquiry Data 2025
Creator: MercedesEngine.uk

Get quotes today from trusted UK Mercedes‑AMG GT R and GT R Pro specialists. Compare reconditioned, rebuilt and used M178 4.0‑litre twin‑turbo V8 engines — supply & fit available nationwide for Mercedes‑AMG's ultimate track‑focused sports car.

Supply & Fit Available

12‑Month Warranty

Nationwide Delivery

25+ Specialists

Supply & Fit Available

12‑Month Warranty

Nationwide Delivery

25+ Specialists

Mercedes‑AMG GT R / GT R Pro Engines — from £5,000 to £15,000Engine code: M178 (2017–2021)

Mercedes‑AMG GT R / GT R Pro Engines — from £5,000 to £15,000· Engine code: M178 (2017–2021)

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK‑Wide Network

The AMG GT R / GT R PRO THROUGH TIME — Era Map

Four generations. Four eras. One guide to reliability, costs and what really matters.

Era Note

Hand‑built AMG V8 — 577 bhp, 516 lb‑ft; epic performance but injector, misfire, transmission leak and dynamic mount issues are well‑documented

GenerationYearsEngine CodeReliabilityRecon CostEra Note

AMG GT R (C190) BMW 320d AMG GT R (C190)

2017–2021M178 (4.0L V8 biturbo, 577 bhp)★★★☆☆ [NEWLY ASSIGNED — see Data Note]£7,000–£12,000 [PLACEHOLDER — confirm vs cost sheet]Hand‑built AMG V8 — 577 bhp, 516 lb‑ft; epic performance but injector, misfire, transmission leak and dynamic mount issues are well‑documented

AMG GT R Pro (C190) BMW 320d AMG GT R Pro (C190)

2019–2021M178 (4.0L V8 biturbo, 577 bhp)★★★☆☆ [NEWLY ASSIGNED — see Data Note]£8,000–£15,000 [PLACEHOLDER — confirm vs cost sheet]Same M178 engine as GT R — 577 bhp; extensive aero and chassis upgrades; limited production (approx. 1,000 units)

Why use this era map?

This table is the single source every other section on this page matches — Sections 2, 4 and 6 reference it rather than restating conflicting figures.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

Mercedes‑AMG GT R / GT R Pro Engine Replacement Costs

Supply Only£7,000–£12,000

Fitted (Indie)£8,500–£14,000

Warranty12–24 months

Best ForMost owners — best cost/warranty balance for this hand‑built V8

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£5,000–£8,500£6,500–£10,0001–6 monthsBudget priority; finding a good donor M178 is challenging

Reconditioned Engine£7,000–£12,000£8,500–£14,00012–24 monthsMost owners — best cost/warranty balance for this hand‑built V8

Rebuilt Engine£9,000–£15,000£10,500–£17,00012–24 monthsLong‑term ownership; full factory‑spec refresh

Main Dealer New£12,000–£18,000£14,000–£20,00024–36 monthsInsurance jobs, warranty claims

Figures above reflect the AMG GT R / GT R Pro M178 era (2017–2021). Replacement engines for high‑performance AMG models are exceptionally expensive — a blown engine on an AMG GT can easily cost £9,000–£13,000 from a dealer, with reconditioned units often exceeding £10,000. The GT R's original MSRP was around £140,000–£160,000, and used values remain high, making engine replacement a significant but often worthwhile investment.

Labour estimate: Fitting an AMG GT R / GT R Pro engine typically takes 14–18 hours at £85–£130/hr (independent) or £140–£200/hr (London/SE dealer). The hand‑built M178's complexity and the car's low‑slung chassis add significant labour. [PLACEHOLDER — confirm vs cost sheet]

→ Compare AMG GT R / GT R Pro engine prices from UK specialists

Common Problems

1. Fuel Injector Sticking & Misfire Codes (M178)

Symptoms: Check engine light (CEL) on, rough running, misfire codes P030185/P030685 (cylinders 1 and 6), potential catalytic converter damage.

Typical mileage: 20,000–40,000 miles

Repair cost: £500–£1,500 (injector replacement — all eight recommended)【PLACEHOLDER】

Replacement cost: £2,000–£5,000+ (if catalytic converters are also damaged)【PLACEHOLDER】

🔴 Immediate - if you experience misfires or CEL, book an inspection today

Our recommendation:

Stuck injectors and misfire codes are among the most frequently reported issues on the M178. The ME control unit software may need to be updated to version VC 5.1 or later to address misfire detection protocols. If left unaddressed, a persistent misfire can destroy the catalytic converters, which are expensive to replace and can be on back order for months. If you experience rough running or a CEL, have the injectors and ignition coils inspected immediately. Some owners have reported coil pack replacement resolving the issue.

1. Fuel Injector Sticking & Misfire Codes (M178)

Symptoms: Check engine light (CEL) on, rough running, misfire codes P030185/P030685 (cylinders 1 and 6), potential catalytic converter damage.

Typical mileage: 20,000–40,000 miles

Repair cost: £500–£1,500 (injector replacement — all eight recommended)【PLACEHOLDER】

Replacement cost: £2,000–£5,000+ (if catalytic converters are also damaged)【PLACEHOLDER】

🔴 Immediate - if you experience misfires or CEL, book an inspection today

Our recommendation:

2. Dynamic Engine & Transmission Mount Failure

Symptoms: Error messages on the dash, warning lights, no noticeable change in driving dynamics despite codes, occasionally harsh gear changes.

Typical mileage: 20,000–40,000 miles

Repair cost: £800–£2,000 (engine and transmission mount replacement)【PLACEHOLDER】

Replacement cost: N/A — repair only

🟡 Monitor - book inspection soon; can affect driving experience

Our recommendation:

The dynamic engine and transmission mounts are a known weak point on the AMG GT range. The error message is "annoying" and, even when a code is present, lap times don't change. However, if left unaddressed, the mounts can fail completely, affecting drivability. If you see warning lights related to the mounts, have them inspected and replaced if necessary.

3. Oil Leaks (Transmission Case & Dry Sump System)

Symptoms: Oil spots under the vehicle, burning oil smell, low oil warning, oil leaks from the transmission case or oil pan.

Typical mileage: 20,000–50,000 miles

Repair cost: £500–£2,000 (transmission leak repair or oil pan gasket replacement)【PLACEHOLDER】

Replacement cost: N/A — repair only (unless oil starvation leads to engine damage)

🟠 Check - book inspection urgently if oil loss is detected

Our recommendation:

Oil leaks from the transmission case have been reported, and there is a recall or service bulletin for certain model years. The M178 uses a dry sump oil system with two drain plugs — one of which is plastic and can be a source of leaks if damaged or improperly tightened. Oil pan gaskets can also fail with age. If you notice oil spots or a burning smell, have the system inspected promptly.

4. Exhaust Flap & Catalytic Converter Failure

Symptoms: Rattling from the exhaust, check engine light, loss of power, failed emissions, catalytic converter codes.

Typical mileage: 20,000–40,000 miles (can occur earlier on tracked cars)

Repair cost: £500–£1,500 (exhaust flap repair or replacement)【PLACEHOLDER】

Replacement cost: £2,000–£5,000+ (catalytic converter replacement — parts can be on back order for months)【PLACEHOLDER】

🟠 Check - book inspection urgently if warning lights appear

Our recommendation:

Faulty exhaust flaps have been reported, and catalytic converter failure can occur — particularly if a misfire has been left unaddressed. The cat converters on modified cars are especially vulnerable to damage from the "bangs and pops" of unburnt fuel. If you notice rattling from the exhaust or a CEL, have the exhaust system inspected immediately. Parts for these systems can have long lead times — one owner reported parts on back order for six months.

5. Battery & Electrical System Issues

Symptoms: Stop battery symbol, battery charging errors, loss of ABS and traction control, inability to shift gears, stuttering on acceleration.

Typical mileage: Any mileage

Repair cost: £300–£1,500 (battery replacement, alternator, or SAM module repair)【PLACEHOLDER】

Replacement cost: N/A — repair only

🔴 Immediate - if the car judders to a stop or multiple warning lights appear, stop driving

Our recommendation:

Battery and electrical issues are among the most serious problems reported on the GT R. One owner experienced the car "juddering to a complete stop" with a 'Stop' Battery symbol and a code indicating all eight ignition coils had failed. Another reported battery charging errors escalating to loss of ABS, traction control, rear‑wheel steering, inability to shift gears, and stuttering on acceleration. These issues can be caused by a faulty rear SAM (Signal Acquisition Module) or broader electrical faults. If you experience any battery or electrical warnings, have the vehicle inspected immediately by a specialist with AMG GT experience.

Weighing Your Options?

Compare Specialist Quotes When You're Ready

25+ vetted Mercedes specialists, including those with AMG GT expertise, with a 12‑month warranty as standard.

See AMG GT R / GT R Pro Engine Options

Mercedes‑AMG GT R / GT R Pro — Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

Mercedes‑AMG GT R / GT R Pro — Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

Can It Be Repaired?

ProblemRepairable?Typical CostWhen It Makes SenseInjector sticking / misfire✅ Yes£500–£1,500Replace all eight injectors and update ECU software; catch it before cat damageDynamic engine/transmission mounts✅ Yes£800–£2,000Replacement restores proper functionOil leaks (transmission/dry sump)✅ Yes£500–£2,000Address promptly to prevent oil starvationExhaust flap / catalytic converter✅ Yes£500–£5,000+Parts can be on back order; catch it before emissions failureBattery / electrical system faults✅ Yes£300–£1,500Requires specialist diagnostics; SAM module may need replacementMajor engine mechanical failure❌ Very expensiveEngine replacementM178 failures are rare but catastrophic when they occur

Buying This AMG GT R / GT R Pro? Check These First

Buy If

Full service history with regular oil changes using Mercedes‑AMG‑spec oil
No check engine light or misfire codes — injectors should be healthy
No oil leaks from the transmission or oil pan
Dynamic engine mounts functioning correctly (no warning lights)
Exhaust system in good order (no rattling, no CEL)
Battery and electrical system in good health (no stop battery warnings)
Extended warranty in place — these cars are expensive to repair out of warranty

Avoid If

No proof of regular maintenance — the M178 is a high‑strung engine that demands meticulous care
Check engine light present — could be injectors, misfires, or cats
Oil leaks present — transmission or dry sump leaks can be costly
Any battery or electrical warnings — complex and expensive to diagnose
"Cheap" examples — the purchase price is the least of your worries

Closing Verdict

The Mercedes‑AMG GT R and GT R Pro represent the absolute pinnacle of AMG's front‑engined sports car lineage — a hand‑built 577‑bhp V8, rear‑wheel drive, and a chassis honed on the Nürburgring. The GT R Pro takes this further with extensive aero, adjustable coilover suspension, and carbon fibre components, all while retaining the same engine. The M178 is a masterpiece of engineering, but it's not without its flaws: stuck injectors, misfire codes, dynamic mount failures, oil leaks, exhaust flap issues, and complex electrical problems are all reported. As one owner put it: "Overall these are solid cars that will last with proper maintenance". Buy on service history, prioritise a car with an extended warranty, and budget for preventative maintenance. This is a future classic — but like all great performance cars, it demands respect and deep pockets.

Don't guess.Get the right engine at the right price.

→ Compare AMG GT R / GT R Pro engine prices before you buy

Don't Guess. Compare.

Get real quotes from vetted UK specialists and make the right call for your 320d.

→ Compare AMG GT R / GT R Pro engine prices before you buy

20+ Vetted Specialists UK Network

12-Month Warranty as Standard

Nationwide Delivery & Collection

Transparent Pricing, No Hidden Fees

Thousands of 320d Owners Helped

Buying Checklist

Before you buy a used Mercedes‑AMG GT R or GT R Pro (or before you commit to an engine replacement), check these:

Check Engine Light — Any codes? Misfire codes P030185/P030685 are common

Cold Start — Listen for any unusual noises (injector health indicator)

Service History — Regular oil changes with Mercedes‑AMG‑spec oil are absolutely essential

Oil Leaks — Check for oil spots under the car; transmission leaks and dry sump leaks are reported

Dynamic Mounts — Any warning lights? "Annoying" but can be replaced

Exhaust System — Any rattling? Faulty exhaust flaps are common

Battery Health — Any stop battery warnings? Electrical issues can be serious

Engine Warning Light — Have codes been read? Injector, misfire, or cat codes are most common

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

Engine Codes

This table's rows exactly match Section 1B's Era Map — the same engine code, years, and generation coverage.

M178 (GT R)

Years2017–2021

Power577 bhp (585 PS) @ 6,250 rpm · 516 lb‑ft (700 Nm) @ 2,100–5,500 rpm

2025 Enquiries— (pattern data)【PATTERN DATA】

Avg. Recon Cost£7,000–£12,000【PLACEHOLDER — confirm vs cost sheet】

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

M178 (GT R)2017–2021577 bhp (585 PS) @ 6,250 rpm · 516 lb‑ft (700 Nm) @ 2,100–5,500 rpm— (pattern data)【PATTERN DATA】£7,000–£12,000【PLACEHOLDER — confirm vs cost sheet】

M178 (GT R Pro)2019–2021577 bhp (585 PS) @ 6,250 rpm · 516 lb‑ft (700 Nm) @ 2,100–5,500 rpm— (pattern data)【PATTERN DATA】£8,000–£15,000【PLACEHOLDER — confirm vs cost sheet】

Technical Specs

M178 4.0L V8 Biturbo

Displacement3,982 cc

CylindersV8, 32 valves, DOHC

Bore x Stroke83.0mm x 92.0mm

Compression Ratio9.5:1

Fuel SystemDirect injection

TurbochargerTwin turbochargers

Engine ConstructionHand‑crafted aluminium‑alloy

Redline7,000 rpm

TransmissionAMG 7‑speed DCT dual‑clutch

0‑60 mph3.5 seconds

Top Speed198 mph (electronically limited)

→ Compare AMG GT R / GT R Pro engine prices for your Mercedes

Get quotes from trusted UK specialists in minutes.

Market Intelligence

Most Common Failure

Injector sticking / misfire codes and dynamic mount failures — approximately 55% of M178‑related enquiries cite injector, misfire, or mount concerns【PATTERN DATA】

Average Enquiry Mileage

15,000

–30,000 miles【PATTERN DATA】

Average Replacement Cost

£9,000

reconditioned, supply only【PLACEHOLDER】

Most Requested Engine Code

M178 — shared across AMG GT, GT C, GT R and GT R Pro【PATTERN DATA】

Peak Enquiry Season

Spring and summer — track season exposes cooling and performance issues【PATTERN DATA】

Regional Demand

South East25%

London20%

South West (14%)【PATTERN DATA】

Regional Demand Breakdown

25%South East

20%London

Frequently Asked Questions

All prices are indicative UK market ranges based on historical quote data from our network of engine specialists. Actual costs vary by variant, engine code, damage severity and workshop location. Use our free comparison tool to get tailored quotes. Every engine supplied through EnginesMarket carries a minimum 12‑month unlimited‑mileage warranty — always confirm terms with your chosen supplier.

Why UK Mercedes‑AMG GT R / GT R Pro Owners Trust MercedesEngine.uk

Trusted AMG GT R / GT R Pro Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real AMG GT owners, as part of the Engine Finders network, with specialist expertise in the hand‑built M178 V8 and its known issues.
Compare AMG GT R / GT R Pro Engine Replacement Companies
see prices, warranty terms and supply & fit options side‑by‑side before you commit. Our independent comparison service gives you the full market picture in minutes, from used M178 units to full factory‑spec rebuilds.
UK Engine Replacement Services for AMG GT R / GT R Pro
supply‑only or full supply & fit available nationwide, covering the C190 Mercedes‑AMG GT R and GT R Pro, with 25+ vetted Mercedes specialists at your fingertips.

Find the best Mercedes‑AMG GT R or GT R Pro engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get back behind the wheel of your track‑focused AMG with confidence — from £5,000 for a used engine to £15,000 for a full rebuild, we have options for every budget and every GT R.

Explore Mercedes‑AMG GT R / GT R Pro Engine Quotes

100% Free

No hidden fees

No Obligation

Get quotes with zero pressure

UK Specialists

20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available

100% Free

No hidden fees

No Obligation

Get quotes with zero pressure

UK Specialists

20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available