What is the P0168 fault-error code?
P0168 fault-error code means "Fuel Temperature Too High" on vehicles. This error indicates that the fuel temperature detected by the engine control unit (ECU) has risen above the set safe limits. Overheating of the fuel can reduce the performance of the engine, increase fuel consumption, and cause serious damage.
Symptoms
You can find the possible symptoms of error code P0168:
Check Engine Light:
The most common symptom is that the engine fault lamp lights up on the dashboard. The ECU turns on this light when it detects that the fuel temperature is above safe limits.
Decrease in Engine Performance:
You may experience performance issues such as loss of power or slow acceleration. Overheating of the fuel can prevent the engine from performing efficient combustion.
Increase in Fuel Consumption:
Excessively hot fuel can cause the engine to run more inefficiently, which leads to increased fuel consumption.
Engine Misfire or Erratic Operation:
A high fuel temperature can cause the engine to misfire, start erratically, or cause fluctuations at idle.
Engine Stalling:
Due to excessively hot fuel, the engine may stall unexpectedly or stop working.
High values in the temperature display:
The temperature indicator on your instrument panel may rise to higher values than usual. This may indicate that the engine is overheating in general.
Black smoke coming out of the exhaust (in some cases):
If the combustion process does not take place efficiently, the fuel may not burn fully and may lead to black smoke coming out of the exhaust.
Causes
There can be several reasons why this error code can be triggered:
Failure of the Fuel Temperature Sensor:
The Fuel Temperature Sensor measures the fuel temperature and sends information to the ECU. When this sensor fails, it may transmit incorrect data and the P0168 code may be triggered.
Fuel System Overheating:
Especially with diesel engines, overheating can occur if the fuel does not cool sufficiently in the return line. This is more likely when working in hot weather conditions or with a high engine load for extended periods of time.
Insufficient Fuel Cooling:
The fuel cooling system (if any) may have failed. Diesel vehicles are equipped with special coolers for cooling the fuel; Their blockage or malfunction can cause the temperature to rise.
Fuel Pump or Filter Blockage:
A clogged fuel filter or faulty fuel pump can restrict the flow of fuel, leading to fuel overheating.
Low Quality Fuel Usage:
Inferior quality or contaminated fuel can cause higher temperatures inside the engine and trigger code P0168.
High Environmental Temperature:
In extremely hot weather conditions, the engine's cooling system may be insufficient, causing the fuel to overheat.
How to Fix
You can find the steps to follow to resolve the error code P0168.
Verify the Error Code with the OBD-II Scanner:
First, read the error code using an OBD-II scanner. Detect not only the P0168 code, but also if there are other errors. If there are other relevant codes (for example, codes related to sensor or fuel pressure), it may be necessary to decode them as well.
Check the Fuel Temperature Sensor:
Fuel Temperature Sensor is a common cause of code P0168. If the sensor is faulty, it may send incorrect data to the ECU.
What to do:
Check the connections of the sensor.
Measure the resistance of the sensor and check if it is working by evaluating it according to the manufacturer's specifications.
Replace the sensor if necessary.
Check the Fuel System and Lines:
Check for problems that may be causing overheating in the fuel system. Inspect the fuel line or return line for blockages or damage.
Check if the fuel filter is clogged. A clogged filter can increase the temperature by restricting the flow of fuel.
Make sure the fuel pump is working properly. A faulty fuel pump can create high pressure, which can cause the fuel to overheat.
Check the fuel cooling system (if applicable):
Diesel vehicles usually have a fuel cooler to cool the fuel. Check if this cooler is clogged or damaged.
If the refrigerant is defective or clogged, clean or replace it.
Battery & Electrical System Control:
Make sure the electrical connections are working properly. Loose or oxidized connections can cause the fuel temperature sensor to transmit incorrect data.
Check the battery voltage; Low voltage can cause the sensors to not work correctly.
Check Fuel Quality:
Inferior quality or contaminated fuel can cause the engine to overheat. Check the inside of the fuel tank and, if necessary, drain the fuel and replace it with clean fuel.
Check Out Engine Cooling System:
Check if the engine's cooling system (radiator, fans, coolant) is working properly. A general overheating of the engine can also cause the fuel to overheat.
Update the Vehicle's Software or Reset the ECU:
In some cases, a software update of the engine control unit (ECU) may be required. You can have your vehicle's software updated from an authorized service.
If you have fixed the problem, reset the error code using an OBD-II device. But if the problem recurs, there may be another problem.
Take a Test Drive:
Once the problem is resolved, take your vehicle for a test drive and check if the error code occurs again. If the problem does not return, the repair was successful.
It is recommended that you contact an authorized service. Problems with complex systems, such as the fuel system and ECU require specialized equipment and specialist knowledge.
Long-Term Effects
Potential problems that error code P0168 can cause to your vehicle overall:
Decrease in Engine Performance:
High fuel temperature leads to inefficient operation of the engine. The elevated temperature in the combustion chamber can prevent the fuel from fully combusting, leading to deficient performance and loss of power.
Overall, this weakens the vehicle's ability to accelerate and negatively affects overall driving pleasure.
Damage to the Fuel System:
If fuel injectors, fuel pump, and other fuel system components are exposed to excessive heat, these parts can become damaged over time.
Especially in diesel engines, overheated fuel injectors and pump can require costly repairs.
Increase in Fuel Consumption:
Overheating of the fuel makes it difficult for the ECU to optimize the engine's mixing ratios. As a result, the engine consumes more fuel.
Engine Overheating:
High fuel temperature can also increase the overall temperature of the engine. This is especially noticeable in vehicles operating in hot weather conditions or under high load.
Engine overheating can cause serious engine failures, such as gasket burnout, cylinder head damage, or piston problems.
Increased Exhaust Emissions:
Fuel exposed to high temperature can increase the engine's exhaust emissions. When the combustion process becomes inefficient, your vehicle's CO₂, NOx and other harmful emissions increase.
This may result in you not passing emission tests.
Ignition Problems:
Overheating of the fuel can lead to spark plug clogging or pre-ignition. This causes the engine to not start properly, misfiring or stalling.
Overall, these problems can lead to further wear on the engine.
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