When it comes to car insurance, many motorists assume that comprehensive coverage protects against all kinds of damage.
However, engine failure often falls into a grey area, leaving drivers wondering whether their insurance will cover the cost of a blown engine.
This guide explains when UK car insurance will pay for engine damage, why mechanical failures are typically excluded, and which additional products can help cover the gaps.
Understanding Engine Failure
What Counts as Engine Failure?
Engine failure refers to any sudden loss of power due to the malfunction or destruction of key internal components. These could include parts like pistons, crankshafts, cylinder head gaskets, oil pumps, or turbochargers. Such damage often leads to catastrophic engine failure.
Typical Causes of Engine Failure:
- Wear and tear: High mileage or poor servicing.
- Over-revving: Often caused by mis-shifting or racing.
- Hydrolock: Caused by floodwater ingestion.
- Fire damage: Under the bonnet, from a vehicle fire.
- Vandalism: Damage to the engine due to theft attempts or intentional harm.
- Misfuelling: Putting petrol in a diesel car or vice versa.
Financial Impact
The cost of replacing an engine can range from £3,000 to £12,000, often surpassing the vehicle’s market value. In many cases, this leads to a total loss settlement by the insurer, which can be a significant financial burden.
UK Car Insurance Basics
Legal Minimum: Third-Party Only (TPO)
TPO insurance meets the legal requirement and covers any injury or damage caused to others. However, it does not cover repairs to your own car, including engine failure.
Third-Party, Fire & Theft (TPFT)
TPFT covers fire damage and theft of your vehicle but excludes coverage for mechanical failure unless the engine was directly harmed by the fire or theft.
Fully Comprehensive Insurance
A comprehensive policy pays for damage to your own car, regardless of fault. This includes incidents like accidents, fires, floods, and vandalism, under which engine damage may be covered. However, failure caused by wear and tear or gradual deterioration is typically excluded.
Optional Add-Ons
Many insurers offer add-ons for specific issues like misfuelling, breakdown cover, or extended mechanical protection. These add-ons come with their own excesses and coverage limits, which should be reviewed carefully.
When Will Car Insurance Pay for Engine Failure?
| Scenario | TPO | TPFT | Comprehensive | Evidence Typically Required | Likelihood of Payout |
|---|---|---|---|---|---|
| Collision you caused | Not covered | Not covered | Covered (subject to excess and write-off thresholds) | Accident report & engineer inspection | High |
| Collision another driver caused | Claim from third party’s insurer | Claim from third party’s insurer | Own insurer then subrogates | Police reference & liability admission | High |
| Fire under bonnet | N/A | Covered | Covered | Fire brigade report & photos | High |
| Theft/attempted theft damages engine loom | N/A | Covered | Covered | Crime ref number, forensic report | Moderate |
| Flood hydrolock while parked | N/A | N/A | Covered (if unavoidable flood event) | Meteorological evidence & assessor strip-down | Moderate |
| Flood hydrolock after driving into deep water | N/A | N/A | Often refused as “avoidable damage” | Dash-cam proof of necessity may help | Low |
| Misfuelling | Usually excluded | Usually excluded | Only if accidental-damage section includes misfuelling or you bought an add-on | Fuel receipt & drain invoice | Low to Moderate |
| Gradual wear, overheating, neglect | Excluded | Excluded | Excluded | Service history proves neglect; claim denied | Nil |
Why Pure Mechanical Breakdown Is Excluded
Insurance is meant to cover sudden, unexpected events rather than predictable deterioration. Since engines naturally degrade over time and through mileage, a general breakdown is viewed as an unavoidable and insurable risk, not a covered event.
Grey Areas and Disputes
Proving Causation
Insurers often employ independent engineers to assess the root cause of engine failure. If the engine shows signs of impact damage, heat damage, or water ingress, the claim may proceed. However, if long-term wear is evident, the claim is likely to be denied.
Avoidable vs Unavoidable Flood Damage
Driving through deep standing water can be classified as driver negligence and may void coverage. On the other hand, a car flooded by flash storms while parked is typically covered.
Misfuelling Nuances
Misfuelling is typically excluded unless the driver has added specific coverage, such as an add-on for misfuelling. Only about 11% of UK policies cover this issue as standard.
Excessive Repair Costs and Write-Offs
If the cost of repairs exceeds the car’s value, insurers may declare the car a write-off and pay the market value instead of covering the engine repair.
Products That Do Protect Against Mechanical Failure
Manufacturer and Extended Warranties
New cars usually come with warranties that cover parts and workmanship. Extended warranties can be purchased for additional protection once the manufacturer’s warranty expires.
Mechanical Breakdown Insurance (MBI)
MBI covers sudden mechanical or electrical failure after the manufacturer’s warranty expires, subject to age and mileage limits, typically around six years or 70,000 miles.
Breakdown Cover
Breakdown services like the RAC and AA can assist with towing but do not cover the cost of engine repairs or parts replacement.
GAP Insurance
In the event of an engine failure caused by an insured incident that leads to the car being written off, GAP insurance can cover the difference between the market value and the original price of the car.
Cost–Benefit Analysis of Extra Protection
| Product | Typical Annual Cost | Protects Against Engine Wear? | Protects Against Accident-Induced Engine Damage? | Key Limits |
|---|---|---|---|---|
| Extended Warranty | £250–£600 | Yes (parts named in policy) | No | Age/mileage caps; servicing compliance |
| MBI | £200–£400 | Yes | Sometimes excluded if collision-related | Claim limit per repair; diagnostics cap |
| Breakdown Cover | £70–£150 | No | No | Labour/parts not included |
| Misfuelling Add-On | £10–£30 | N/A | Yes (drain & flush only) | £1,000 limit, excess applies |
| GAP (3-year) | £150–£350 | Indirect—covers total loss valuation gap | Yes, if car is write-off | Vehicle age and finance ceiling |
How to Protect Yourself
Preventive Maintenance
Regular servicing, oil changes, and coolant checks can drastically reduce the risk of engine failure and ensure any existing warranties remain valid.
Choose the Right Policy
If you live in an area prone to floods, look for comprehensive coverage that explicitly includes water damage. High-mileage drivers may benefit from additional warranties that cover engine failure.
Read the Fine Print
Be aware of exclusions such as “wear and tear,” “mechanical or electrical breakdown,” and “corrosion,” as these are often not covered under standard insurance policies.
Claim Preparation Checklist
- Cease driving immediately to prevent further damage.
- Photograph the damage and any relevant evidence (water line, impact damage).
- Obtain witness statements or police reports if necessary.
- Keep receipts for recovery, diagnostics, and storage.
- Submit your claim within the time-frame specified in your policy (usually within 24-48 hours).
Conclusion
In the UK, car insurance will generally only cover engine repairs if the damage is caused by an insured event, such as a collision, fire, theft, or unavoidable flood. Mechanical breakdowns due to wear and tear, misfuelling, or gradual damage are typically excluded. To avoid hefty repair costs, consider combining a comprehensive policy with an extended warranty or mechanical breakdown insurance, maintain your vehicle regularly, and fully understand your policy’s exclusions.
