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How to Clear Engine Derate: A Detailed Guide

Engine derate is an ECM feature that restricts engine power to save the engine from harm. The electronic control module, sometimes called the ECM, is the car’s computer. The ECM continuously checks the engine’s health and reduces power when it detects a potential issue.

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What Is Engine Derate?

The engine derates generally means that the computer software controlling the automotive engine restricts the vehicle’s speed or power. Engine derate is a self-protective, or load-limiting, feature pre-programmed into the working software of most modern diesel engines. This method keeps the engine from overheating when lowering power. Each motor is built to function in a given environment with specific environmental conditions. The motor relief is designed to start when the outside temperature rises over the level required for regular operation. An engine’s overall performance is drastically reduced when it enters derate as self-defense.

Causes of Engine Derate

One of the main reasons for the engine’s derate is the exhaust gas temperature. To prevent damage to the engine, the ECM will restrict power when your engine is running too hot. Low oil pressure is another typical reason for engine derailment. Your engine may suffer harm if its oil pressure is too low. Another reason may be if the coolant temperature in your vehicle is too high. Your engine may run lean if the fuel pressure inside of it is low. Running poorly indicates insufficient gasoline in the fuel and air combination. It may harm the engine as a result.

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How To Clear Engine Derate Code

Correcting an error and addressing its primary cause is the most effective strategy. For instance, just removing the error number won’t solve the real issue if a broken water pump brings on a malfunction. Keeping your engine running while a water pump fails can exacerbate the harm already done.

A fault code that appears on the dash typically indicates an engine derates. If a fault code appears, you should turn off the engine and check your owner’s handbook to find out what it implies. The code is often shown as Spn1209.

While a typical OBD2 scanner can read and understand this code, some automobile models need an OEM-specific gadget to delete the error code. The best action would be to bring your car to the dealership and have them take care of it if you don’t have access to an OEM-specific tool.

How to Fix Engine Derate?

The list of minor fixes is provided below in case your car depreciates, and you wish to fix it to get it back to regular operation.

  • Fix the underlying problems and remove any fault codes that cause derating. 
  •  By addressing the underlying problems, derating fault codes can be eliminated.
  • To help the engine restart efficiently, reset the counter to zero.
  • Restart your engine three times to get confirmation that it is working back to normal.
  • If the repair confirmation is unsuccessful, you will need to restart your engine immediately because it would have derated during that time.
  • After you’ve fixed that problem, restart your engine using an incentive counter and give it around 30 minutes. The machine will return to regular operation after no defects have been found throughout the time frame.


What does your engine derating mean?

Engine derating decreases an engine’s output to compensate for less-than-ideal operating conditions. Derating may occasionally be done on purpose to prolong the engine’s life and avoid severe strain or damage.


What causes an engine power reduction?

Engine power drops and efficiency declines when ambient temperature increases over designated operating levels. Increased engine fluid temperatures brought on by cooling system flaws can result in a more significant loss of engine power and an increase in fuel consumption.

How engine are derates calculated?

The 15kW derating ratio is calculated by dividing the engine’s maximum output of 20kW by the maximum output of 15kW at 20% diesel, or 75%.

What Leads to the Derating of a Diesel Engine?

The engines are in danger because they have started to lose efficiency if the temperature rises over the specified operating parameters. Inadequately installed cooling systems can cause engine fluid temperature to increase, leading to engine failure and a considerable drop in fuel efficiency.

What are a Few Typical Engine Derate Causes?

Among the frequent reasons for engine derate are:

  • Inadequate oil pressure
  • Increased coolant temperature
  • Too little fuel pressure


When the question arises of how to clear engine derate, remember, even while you may eliminate the derate issue by only erasing the error codes with an OEM, it is recommended that you identify and address the problem’s primary causes. For instance, driving farther can only harm your engine if the malfunction is due to a broken water pump.

As a result of operating under unique circumstances, an engine running under derating may last less time. It is usually advised for the user to use their vehicle’s engine without any restrictions. Therefore, removing the error could seem the easiest option, but addressing the root cause is preferable, aiding in additional engine damage.


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