Renault Megane DTC253F29 / P253F – Engine Oil Dilution & DPF Regeneration Fault

DPF & Diagnostic Specialists – Hartlepool

We recently had this Renault Megane in with an engine management fault relating to DTC253F29 / P253F – Engine Oil Dilution.

This is a fault that is commonly associated with the vehicle’s DPF regeneration system, and it shouldn’t simply be cleared without investigating why the oil dilution value has become excessive.

🔧 What Does DTC253F29 Mean?

DTC253F29 is associated with engine oil dilution. On Renault diesel models, the ECU calculates oil dilution based on factors including the vehicle’s DPF regeneration activity.

During a DPF regeneration, additional fuel can be injected to raise exhaust temperatures and burn accumulated soot from the DPF.

If regenerations are repeatedly interrupted or unsuccessful, the vehicle can end up carrying out frequent regeneration attempts. Some of the additional fuel can make its way into the engine oil, increasing the calculated oil dilution level.

This can eventually trigger P253F / DTC253F29 and may prevent further DPF regeneration until the issue is addressed.

⚠️ Why Is Oil Dilution a Problem?

Fuel-diluted engine oil can become thinner than intended, reducing its ability to properly protect internal engine components.

That means this isn’t simply a warning light that should be ignored.

If the vehicle is continuing to attempt regenerations frequently, the underlying DPF issue needs to be investigated rather than repeatedly clearing the fault code.

🚗 What Can Cause It?

There are several possible causes, including:

• Frequent short journeys

• Repeated interrupted DPF regenerations

• A partially blocked DPF

• Excessive soot or ash accumulation

• Faulty DPF pressure or temperature sensors

• Issues with the regeneration system

• Other engine or fuelling faults causing excessive DPF loading

• 
  

The exact cause needs to be established through proper diagnostics rather than assuming the DPF itself is automatically at fault.

🔍 Our Diagnostic Approach

When we see a fault such as DTC253F29, we don’t simply erase the code and send the vehicle away.

We can assess the vehicle’s DPF system, check relevant live data and investigate the regeneration history and associated parameters.

Where appropriate, the DPF can then be cleaned to remove accumulated contamination and restore the filter’s ability to operate correctly.

An oil and filter change may also be required where the engine oil has become contaminated with diesel, followed by the necessary service/oil dilution resets using suitable diagnostic equipment.

💡 Don’t Just Clear the Fault Code

Clearing P253F/DTC253F29 without addressing the reason behind the fault can result in the warning returning.

More importantly, continuing to drive a vehicle with excessive oil dilution can potentially put unnecessary stress on the engine.

If your Renault is showing P253F, DTC253F29, “Check Injection”, “Check Anti-Pollution System” or DPF-related warnings, it is worth having the vehicle properly diagnosed before the problem develops into a more expensive repair.

📍 Advanced Remaps & DPF Cleaning

Based in Hartlepool, we specialise in DPF diagnostics, DPF cleaning and vehicle diagnostics.

If your Renault, Nissan or Dacia diesel is suffering from repeated DPF regenerations or an engine oil dilution fault, get in touch with us to arrange a diagnostic assessment.

Advanced Remaps & DPF Cleaning

📍 Hartlepool

🔧 DPF Cleaning & Diagnostic Specialists

DTC253F29/P253F can have different underlying causes. Proper diagnosis is recommended before carrying out repairs or replacing components.