Explanation of Code P242F: “Diesel Particulate Filter (DPF) – Ash Accumulation”
Severity
- Level : 🔴 High (risk of complete DPF clogging, engine damage, and major additional costs).
- Urgency :
- Significant power loss.
- Risk of DPF failure (replacement cost: €800 to €3000).
- Failure in technical inspection (excessive pollutant emissions).
Symptoms
- 🚗 Power loss (weak acceleration, especially uphill).
- 🌫️ Black smoke from the exhaust.
- ⚠️ Engine warning light on (MIL) and/or flashing DPF light.
- 🔥 High temperatures of the engine and exhaust.
- ⛽ Increased fuel consumption (up to +30%).
Main Causes
- Excessive ash accumulation :
- Origin : Unburned combustion residues (engine oil, poor-quality fuel).
- Aggravating factors : Frequent short trips (prevent passive regeneration).
- Regeneration system malfunction :
- Interrupted active regeneration (e.g., engine shutdown during the process).
- Faulty temperature sensor or defective lambda sensor.
- Mechanical/electrical problems :
- Faulty differential pressure sensor or clogged tubes.
- Exhaust leaks (cracked manifold gaskets).
- Faulty injectors (poor fuel atomization).
Diagnostic Procedure
Step 1: Reading OBD2 codes and data
- Use a compatible diesel scanner (e.g., Autel DS808 or Launch X431) to:
- Check differential pressures before/after DPF.
- Analyze the ash counter (grams accumulated).
Step 2: Visual inspection
- Check the pressure sensor tubes (detached, melted, or clogged).
- Look for exhaust leaks (localized smoke, damaged gaskets).
Step 3: Differential pressure sensor test
- Resistance measurement : Compare with manufacturer specifications (e.g., 4.6 kΩ at 20°C).
- Vacuum test : Use a vacuum pump to check sensor responsiveness.
Step 4: Regeneration conditions check
- Fuel level : Must be > 25% to initiate forced regeneration.
- Coolant temperature : > 70°C.
Solutions & Costs
| Solution | Procedure | Average Cost |
|---|---|---|
| Forced regeneration | Via scanner or dedicated button (depending on model) | €50 – €150 (garage) |
| Chemical DPF cleaning | Use of additives (e.g., Wynns DPF Cleaner) | €30 – €80 |
| DPF replacement | Necessary if clogging > 90% | €800 – €3000 |
| Pressure sensor replacement | New sensor + recalibration | €100 – €300 |
| Exhaust leak repair | Replacement of gaskets/manifold | €200 – €600 |
Pro Tips
- Avoid short trips : Prefer trips > 20 minutes at high RPM (2500-3000 rpm) to promote passive regeneration.
- Use low-SAPS oils : Specific for diesel engines equipped with DPF (e.g., Total Quartz INEO ECS).
- Monitor the ash counter : Via a scanner, trigger DPF replacement before 180,000 km (depending on manufacturer).
Mistakes to Avoid
- ❌ Ignoring the DPF light : Complete clogging can immobilize the vehicle.
- ❌ Forcing regeneration without diagnosis : Risk of overheating or fire.
- ❌ Using unapproved additives : Can damage catalysts.
Practical Case
- Problem : Code P242F on a Peugeot 308 1.6 HDi with power loss.
- Diagnosis : Ash counter at 45g (manufacturer limit: 40g).
- Solution : Forced regeneration via scanner + cleaning of sensor tubes.
Frequently Affected Vehicles
- Peugeot/Citroën : 308, 3008, 508, C4 Picasso.
- Renault : Mégane, Scénic, Kadjar.
- Ford : Focus, Kuga (1.5/2.0 TDCI engines).
Warnings
- ⚠️ Handling exhaust gases : Extreme temperatures (risk of burns).
- ⚠️ Professional repair recommended for forced regenerations or DPF replacements.
If the DPF is too clogged, regeneration alone will not suffice: consult a specialized garage to avoid engine damage! 🔧🚗