Buying a Used EcoBoost, PureTech or Modern Diesel? Read This First

Efficient engines, with a few catches

These engines power a huge share of the used cars on UK forecourts, and most are efficient and perfectly capable. But a few have well-documented weak points that can turn into big bills if you buy blind. Here's what to know about EcoBoost, PureTech and modern diesels before you hand over any money - and how to keep one healthy once it's yours.

Ford EcoBoost: the wet belt

Ford's EcoBoost 1.0 petrol uses7 a wet belt - a timing belt that runs inside the engine in oil. Over time it can shed material into the oil, block the oil pump pickup and, in a worst case, wreck the engine. They're fine when looked after, but you need to know the belt's history and budget for replacement.

Before you buy, ask when the belt was last changed, check the oil for debris, and listen for a rattle on cold start. We go into the detail in our guide to the hidden risks of wet belts.

PSA / Stellantis PureTech

The 1.2 PureTech (and 1.0) used the same wet belt approach and has been the most talked-about of the lot, with belt degradation and high oil consumption on the earlier engines.

There's good news for buyers, though. From 2023 Stellantis began switching to a timing chain, starting with the hybrid versions, so the newest engines are much less of a worry. The catch is that during the 2023 to 2025 changeover both versions were on sale, so even a fairly new car can still have a belt - and the badge won't tell you. Stellantis dropped the "PureTech" name in late 2024 in favour of "1.2 Turbo" or "1.2 Hybrid", but some of those still have the older wet belt engine underneath. The only reliable way to know is the engine code.

Worth knowing: Stellantis has extended the warranty on the older 1.0 and 1.2 PureTech engines to up to 10 years or around 112,000 miles, and runs a compensation scheme for owners who paid for belt or oil-consumption repairs between January 2022 and December 2024. Eligibility depends on service history and conditions, so it's worth checking directly with the manufacturer. Either way, a full history matters even more than usual on these. If yours needs the belt doing, that's a wet belt replacement we carry out regularly.

Modern diesels: the DPF and friends

A modern diesel can be a brilliant motorway car, but it's the wrong choice for mostly short, local journeys. The diesel particulate filter (DPF) needs regular runs at speed to burn off soot; lots of short trips and it clogs - and a new DPF is expensive. If you mainly potter about town, a petrol or hybrid will usually suit you better.

Other things to watch on a used diesel: the EGR valve, injectors, the dual-mass flywheel, the AdBlue and emissions systems on Euro 6 cars, and oil dilution from DPF regeneration. Some Ford EcoBlue diesels also use a wet belt. None of these are deal-breakers, but they reward a careful history check - and a blocked filter is often a symptom of something else, which is why DPF work should always start with a proper diagnosis.

What to check before you buy

Whatever the engine, a few checks tell you a lot.

Full service history
Proof of the right oil, the right intervals, and any belt or DPF work that's been done.

Cold-start it yourself
Listen for rattles or ticking in the first few seconds, and watch for smoke from the exhaust.

Check the oil
Look at the level and condition - debris or a strong fuel smell are red flags.

Warning lights
Make sure none are lit, and be wary if they look like they've recently been cleared.

Get it checked
A diagnostic or pre-purchase once-over can flag problems before you commit.

How to look after one once it's yours

Most of these engines are reliable if you treat them right.

Use the correct oil and keep to the schedule
Stick to - or beat - the service schedule, especially on wet belt engines.

Change the wet belt on time
Don't wait for symptoms - replace it at the right interval and you avoid the worst-case bill.

Give a diesel a proper run
Regular longer journeys let the DPF regenerate and keep it clear.

How West Auto can help

Whether you've just bought one or you're about to, we can help you keep it healthy. We carry out wet belt replacement, DPF cleaning, servicing and diagnostics for Ford, PureTech and diesel engines across Newcastle and the North East - and we'll give you a straight answer on what your car actually needs.

Thinking of buying and want a second opinion first? Call us on 0191 271 1605 or enquire online - we're glad to help.

Used engine FAQs