Short answer / Key takeaway: This guide is for UK Mazda owners, workshop mechanics and engine buyers investigating a PEX4 reference, e-Skyactiv-G problems or replacement options. Mazda documents relevant 2.0-litre SKYACTIV-G petrol and M Hybrid specifications, but the reviewed sources do not prove the exact PEX4 mapping, so confirm the registration, physical engine identity and electrical/control configuration before ordering. Then compare tested used, reconditioned or supply-and-fit quotes by evidence, included hardware, warranty and fitting scope.
MAZDA ENGINE CODE • PEX4
Mazda PEX4 Engine (2.0L e-Skyactiv-G): Specs, Common Faults & Replacement
Mazda PEX4 2.0L e-Skyactiv-G engine guide for the Mazda 3, CX-30 - specs, common faults and reconditioned or tested used replacement options with warranty.
✓ Used & reconditioned routes
✓ Supply only or fitted
✓ Vehicle-specific checks before commitment
ENGINE SIZE
2.0L
FUEL TYPE
Petrol (Mild Hybrid)
ENGINE CODE
PEX4 replacement engine options
Related engine size:Mazda 2.0L Engines →
UK's Most Requested Engines — Based on 5,760+ Real Quotes (Last 90 Days)
These are the engines UK drivers ask us about most, ranked by real enquiry traffic through our network — useful context when you're weighing how much homework your engine deserves.
1
Most requested
Mazda 6 2.2 SkyActiv-D Engine SH-VPTR / SHY family
Used & reconditioned · Business seller
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Typical fitment: Mazda 6
Engine option: SH-VPTR / SHY family
Top UK demand — the diesel most often researched for replacement
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2
Mazda CX-5 2.2 SkyActiv-D Engine SHY1 / SHY4 / SHY6
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: CX-5
Engine option: SHY1 / SHY4 / SHY6
High demand; output and code vary by year
Seller from trusted UK supplier network
3
Mazda 3 2.0 SkyActiv-G Engine PE-VPS
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: Mazda 3
Engine option: PE-VPS
Volume petrol with several applications
Seller from trusted UK supplier network
4
Mazda CX-3 1.5 SkyActiv-D Engine S5-DPTR
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: CX-3
Engine option: S5-DPTR
Steady CX-3 DK diesel demand
Seller from trusted UK supplier network
5
Mazda 2 1.5 SkyActiv-G Engine P5-VPS
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: Mazda 2
Engine option: P5-VPS
Small-car petrol volume
Seller from trusted UK supplier network
6
Mazda MX-5 1.5 / 2.0 SkyActiv-G Engine
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: MX-5
Enthusiast-driven demand
Seller from trusted UK supplier network
7
Mazda CX-60 3.3 e-Skyactiv D Engine T3Y4
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: CX-60
Engine option: T3Y4
Newest diesel; near-new donor market
Seller from trusted UK supplier network
8
Mazda CX-30 2.0 SkyActiv-G Engine PE-VPS / PEX family
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: CX-30
Engine option: PE-VPS / PEX family
Growing volume
Seller from trusted UK supplier network
9
Mazda BT-50 3.2 Duratorq diesel Engine P5-AT
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: BT-50
Engine option: P5-AT
Commercial workhorse demand
Seller from trusted UK supplier network
10
Mazda 2.5 SkyActiv-G Petrol Engine
Used & reconditioned · Business seller
Get multiple engine quotes across the UK
Typical fitment: CX-5, Mazda 6, CX-30, Mazda 3
Higher-capacity petrol
Seller from trusted UK supplier network
Reviewed Mazda engine guidance
Reviewed by the MazdaReplacementEngines.co.uk technical content team. Last updated: 21 September 2026.
Important buying questions
Top Summary / Key Takeaway
If PEX4 appears in a Mazda 3 replacement-engine enquiry, do not order a unit from the code reference alone. Mazda documentation confirms 2.0-litre Mazda3 petrol configurations and mild-hybrid variants in relevant specifications, but the reviewed manufacturer evidence does not by itself establish PEX4 as the exact engine code. UK owners and workshops should verify the registration, physical engine identification and vehicle configuration before comparing replacement options.
Who this guide is for
Audience / use case
This page is for UK Mazda owners, garages and replacement-engine buyers who have been given a PEX4 reference and need to identify the correct engine, decide whether complete replacement is justified and compare tested used, reconditioned or supply-and-fit options.
Engine definition
What is PEX4 on a Mazda engine enquiry?
PEX4 should be treated as an engine identifier that needs vehicle-specific verification. Do not assume that the identifier alone proves engine capacity, mild-hybrid configuration, output or compatibility with a particular Mazda 3.
Source-backed information
What does Mazda officially confirm about Mazda3 2.0 petrol engines?
Mazda's official Mazda3 specifications document SKYACTIV-G 2.0 as a DOHC 16-valve inline-four with 1,998 cc displacement and 83.5 × 91.2 mm bore and stroke in the specification reviewed. Mazda documentation also shows that some SKYACTIV-G 2.0 Mazda3 configurations use M Hybrid hardware. These facts provide manufacturer context, but they do not prove the PEX4 code mapping.
External link 2
Mazda Motor Corporation — Mazda3 Owner's Manual, Electrical System / M Hybrid: https://owners-manual.mazda.com/gen/en/mazda3/mazda3_8hs5ee19i/contents/10020102.html
Verification data to record
| Manufacturer-backed context | Value |
|---|---|
| Mazda3 SKYACTIV-G 2.0 displacement | 1,998 cc |
| Layout | DOHC 16-valve inline-four |
| Bore × stroke | 83.5 × 91.2 mm |
| M Hybrid context | Mazda documentation lists SKYACTIV-G 2.0 among engines with M Hybrid in relevant specifications |
| Evidence limitation | None of these values independently establishes PEX4 as the engine code |
Compatibility and fitment checks
Does PEX4 definitely fit my Mazda 3?
Not from the code reference alone. Match the UK registration and physical engine identification to the production period, derivative, transmission/drivetrain, emissions/electronic specification and any mild-hybrid/control hardware before accepting a replacement.
Diagnosis before replacement
Should I replace the engine because of a warning light or poor running?
No, not automatically. Diagnostic scanning and appropriate mechanical checks should separate internal engine damage from ignition, fuelling, intake, cooling, lubrication, emissions, sensor, electrical or mild-hybrid/control faults before a complete engine is authorised.
Repair or replacement decision
| Route | Compare |
|---|---|
| Tested used | Exact identity, disclosed mileage, provenance, testing/condition evidence, included components/electronics, supplier warranty |
| Reconditioned | Documented work, replaced parts, inspections/measurements, test results, included hardware, supplier warranty |
| Supply & fit | Verified engine, removal/installation, fluids/filters, ancillary/electrical transfer, relevant coding/adaptation, commissioning, road test, timing and warranty |
Which PEX4 replacement route should I compare?
After identity and diagnosis are confirmed, compare tested used, reconditioned and supply-and-fit routes on evidence, included components, warranty, total cost and installation scope rather than headline price alone.
Verify the engine before ordering
Confirm UK registration and vehicle specification.
Record or photograph the physical engine identification.
Confirm production period and derivative.
Confirm transmission and drivetrain.
Confirm emissions, electronics and any mild-hybrid/control configuration.
Review used-engine mileage/provenance/testing evidence or reconditioning records.
Confirm included components/electronics.
Get warranty, delivery and fitting scope in writing.
How do I verify PEX4 before buying?
Start with the UK registration, then record the physical engine identification and require the proposed replacement to be matched to the individual vehicle in writing. Where mild-hybrid equipment is present, confirm the relevant electrical/control configuration and installation requirements too.
Practical matching example
What real evidence should support a PEX4 replacement?
Use genuine evidence from the actual engine or supplier process: physical identification photographs, donor/provenance records, disclosed mileage, inspection/testing records or documented reconditioning work. Do not invent screenshots, tests, customer cases or first-hand experience for SEO purposes.
When available, publish an owned engine-identification photo, anonymised supplier test checklist or condition/reconditioning report with a short explanation of what it proves. Remove customer-identifying information before publication.
Concrete original-evidence implementation.
What to compare in a quote
What should a PEX4 replacement-engine quote include?
The written quote should identify the proposed engine and state condition, used-engine mileage where applicable, price, warranty, delivery, fitting if requested, expected timing and supplier identity/details. Compare quotes only after suppliers are working from the same verified requirement.
Relevant suppliers can send quotes by email and SMS/WhatsApp after an enquiry. Availability is confirmed after the enquiry rather than shown as real-time stock, and MazdaReplacementEngines.co.uk does not charge customers for its quote-comparison service.
PEX4 engine FAQs
What is PEX4?
PEX4 is an engine identifier that should be verified against the individual vehicle. Do not use the identifier alone as proof of capacity, output or compatibility.
Can I order PEX4 using my registration alone?
The registration is the vehicle-level starting point, but physical engine identification and the relevant vehicle/electrical specification should also be checked before compatibility is accepted.
Can I buy a tested used PEX4 engine?
Where a correctly matched unit is available, compare exact identity, disclosed mileage, provenance, testing/condition evidence, included components and supplier warranty.
Can I get a reconditioned PEX4 engine?
Where a matching option is available, compare documented work, replaced parts, inspections or measurements, test results, included hardware and supplier warranty.
Can I request PEX4 supply and fit?
Yes, where a suitable matched unit and workshop route are available. The quote should define installation, relevant coding/adaptation, commissioning, road testing and warranty.
How much does a PEX4 replacement engine cost?
There is no reliable single price because cost depends on exact identity, condition, used mileage where applicable, availability, included components, delivery and fitting requirements.
Does a warning light mean I need another engine?
Not automatically. Diagnostic evidence is required because electrical, sensor, ignition, fuelling or other faults can produce serious symptoms without proving complete internal engine failure.
Does mild-hybrid equipment affect engine replacement?
It can. If the individual Mazda 3 is equipped with mild-hybrid hardware, confirm the relevant electrical/control configuration, included components and installation requirements.
Should PEX4 be indexed now?
Not until the exact PEX4 application is technically verified and the corrected page is published. While verification is pending, keep the page noindex but allow follow where appropriate.
Reviewed Mazda engine guidance
Reviewed by the MazdaReplacementEngines.co.uk technical content team. Last updated: 16 September 2026.
About this service
Entity statement
MazdaReplacementEngines.co.uk is an independent UK replacement-engine comparison service for Mazda owners and workshops and is not affiliated with Mazda Motor Corporation.
Depth
Depth/topical coverage
Replace the thin ~194-word body with the corrected sections above. This adds definition, manufacturer-backed context, compatibility, diagnosis, decision support, verification, genuine evidence guidance, quote criteria and expanded FAQs without altering audit items that already PASS.
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