ENGINE FAILURE HAZARD is an error message commonly seen in Renault cars. It appears in red on the LCD screen and is accompanied by a warning chime. The possibility of imminent engine failure can be nerve‑wracking, especially if you’re far from a city or repair shop.
Even if this message shows up on the dashboard, it doesn’t necessarily mean the car will break down within the next few miles. Drive carefully and avoid high engine speeds, as extreme RPMs, temperatures, and pressures can make the issue worse. Head to an auto repair shop for a professional diagnosis. The error can be triggered by various faulty components — such as sensors, electrical connections, a clogged diesel particulate filter (DPF), or the inability to regenerate the DPF.
ENGINE FAILURE HAZARD – Clogged Particulate Filter
In many cases, this error is caused by a clogged diesel particulate filter (DPF). The engine control unit (ECU) monitors the DPF clogging level by measuring pressure differences before and after the filter using two sensors.
In 1.5 dCi Euro 5 engines with a DPF — which regenerates using a fifth diesel injector on the fuel rail — this error is especially common.
After the ENGINE FAILURE HAZARD message appears, the DPF can be manually regenerated at a Renault service center using diagnostic software. This forced regen takes about 30 minutes and typically costs around $45–$70 USD depending on the shop.
DIY Option:
Some owners try to perform the regeneration themselves:
- First, check the error using an OBD‑II scanner like an ELM327 or a Delphi DS150 connected to the vehicle’s OBD port. On many Renault models, the OBD port is located on the center console below the start card slot.
- I make sure the error is P242F, which indicates ash accumulation in the particulate filter, and not errors caused by faulty sensors or probes.
- I check the oil level.
- I reset the service interval for maintenance (important for calculating oil dilution).
- I make sure to fill the tank with premium diesel with a high cetane rating.
- I clear the stored errors in the ECU using the Torque app on my phone and an ELM 327 reader.
- I start driving, ensuring the coolant temperature is sufficiently high, and keep the engine between 1800 and 2400 RPM.
If the car has faulty sensors or probes, the errors will reappear, indicating a professional diagnostic is needed.
At this stage, the car will detect the particulate filter clog again and restart the regeneration process. Ash deposits in the catalytic converter, sensors, and particulate filter are burned off both during the regeneration process (when diesel is injected via the fifth injector on the fuel rail) and passively during normal driving.
To complete the regeneration and prevent the error from returning, you should maintain a constant engine speed between 1800 and 2500 RPM, in fourth, fifth, or sixth gear, for about 12–15 km (7–9 miles). During this time, you should not exceed the two RPM thresholds.
Regeneration should not be done at high RPMs. High engine speeds can increase turbo temperatures and damage critical engine components, especially when the particulate filter is clogged and exhaust gases cannot flow freely. At the same time, engine speed should be kept above 2000 RPM to prevent the exhaust temperature from dropping too low during regeneration.
Renault 1.5 dCi Euro 5 cars with a particulate filter that have exceeded 200,000 kilometers (about 124,000 miles) will frequently trigger this error, and regenerations will become very frequent. If you have such a car, especially if you mostly drive in the city, you should consider professional cleaning of the particulate filter or replacing it (a relatively expensive operation).
Also, clean the EGR valve to ensure proper gas recirculation according to the EGR map stored in the ECU. Gas recirculation helps reduce both emissions and particulate matter that could contribute to clogging the filter.
Completely removing the particulate filter is technically effective, but it is not legal. The vehicle will no longer meet the manufacturer’s emission standards. During a state vehicle inspection (safety/emissions check), this can be detected, and the owner may be required to reinstall a new filter.
I have selected a very good tutorial for you that clearly explains the role of the particulate filter in simple terms.
