Codes This Page Will Cover
- P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control
- P0126 Insufficient Coolant Temperature for Stable Operation
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What Is the P0125 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
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Difficulty of Inspecting
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The diagnostic code P0125 has to deal with the cooling system in your vehicle and the Engine Control Module (ECM) not detecting enough heat from the engine before the fuel management system takes control. It essentially means that your engine is running very cold and that the ECM has not detected a predetermined coolant temperature value.
This issue is also related to the P0126 code that occurs when the engine doesn’t reach normal operating temperatures within a specified period. When the engine reaches its specified operating temperature range, the ECM can control the fuel and ignition systems. This temperature range is typically between 195 to 220 degrees Fahrenheit; however, these specific values depend on the vehicle’s make.
What Are the Symptoms of a P0125 Code?
The first symptom that you will encounter with either the P0125 or P0126 code is that the ECM in your vehicle will set the Check Engine Light on your dashboard. You might also notice poor fuel economy since the ECM might not be able to control the correct air and fuel mixture needed to run your engine normally. There is usually a lack of heater performance that accompanies these symptoms, but, usually, you will not run into any driveability issues. You might witness engine damage in rare cases, but this only occurs if you ignore the problem for prolonged periods.
What Are Some Causes of a P0125 Code?
The P0125 issue is usually the result of a disconnected plug to the engine coolant temperature sensor (ECT) or even corrosion in the ECT sensor connector. If there is damage to the ECT sensor wiring that leads to the ECM, then this will trigger the code. Or, more simply, you may be dealing with a faulty or damaged ECT sensor itself. If the engine is low on coolant or is experiencing coolant leaks, then this will trigger the P0125 code. Another cause is consistently operating your vehicle for short periods of time when outside temperatures don’t allow for the engine to reach a normal operating temperature. Also, if the engine coolant thermostat is not opening at the proper temperature, then this will likely set the code. Finally, a damaged or defective ECM may cause the P0125 code, but this is very unlikely.
How Serious Is the P0125 Code?
As mentioned, the P0125 code will more than likely not present any driveability issues. However, it can cause your engine to overheat, which can be potentially really dangerous to the health of your engine and can lead to fuel instability which can damage your engine. As we have seen, it can affect your fuel economy and your ability to pass emissions tests, so this code is a potentially very critical code to consider. You should make sure to address this code as soon as you are aware of it to prevent any further damage to your engine. The best thing to do is to take your vehicle to a certified service center as soon as you’re able to, and have a qualified technician inspect your car.
Can I Still Drive with a P0125 Code?
We have mentioned that the P0125 code usually will not present any physical driving symptoms to prevent you from operating your vehicle normally. However, it has the potential to cause engine overheating and damage to your internal components if you ignore it long enough. This is why it’s not recommended to drive with the P0125 code. Instead, you should take your vehicle to a technician right away to properly diagnose and repair any present issues.
How Easy Is It to Diagnose a P0125 Code?
The diagnostic process of a P0125 code usually begins with a technician using an advanced scan tool to read the stored codes and available freeze frame data. They will use the scan tool alongside an infrared thermometer to compare temperature readings to match manufacturer specifications. They will also check the coolant level when the engine is cold and proceed to check the engine cooling fan and the ECT sensor to assess its operation. The process can be time-consuming as many causes can lead to the P0125 and P0126 issues. It’s important not to make the mistake of concluding that the thermostat is the cause of the problem before visually inspecting other cooling components. It’s also important to make sure that you bleed the cooling system properly to remove any air pockets that can cause overheating.
How Difficult Is It to Inspect a P0125 Code?
As we have shown, the diagnosis of the P0125 issue can be time-consuming as it can stem from a variety of different causes. This is why you should allow a qualified technician with previous experience with these issues to inspect your vehicle. It’s not recommended to DIY the inspection process at home because you can misdiagnose the problem and cause further damage to your vehicle.
A qualified technician will verify the engine coolant level, ensure that the thermostat is opening correctly, and road test the vehicle to determine where the issue is coming from. They will use the scanning tool, thermometer, and a voltage meter to isolate the cause of the issue. If there are wiring issues or coolant leaks, then they will repair those before testing the vehicle again for the problem. If the issue lies with the cooling fan or other cooling system components, then they will replace the parts as needed. Furthermore, if the issue lies with the ECT sensor or its wiring harness, then they will replace those parts to ensure that the problem goes away.
Need Additional Help with Your P0125 Code?
The P0125 code is critical, but it doesn’t have to lead to further damage to your engine if you take the correct steps to inspect and repair the issue. By following our guidelines here, you’ll be able to keep your vehicle running smoothly for longer and avoid unnecessary repair bills.
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