P0128 Code – What it Mean & How Long can You Drive?

Vehicles nowadays come with a variety of codes nowadays, each of which is there for some definite purpose and have their unique meaning. However, some of the codes are not very commonly understood by everyone as they appear rarely.

P0128 is another such code which basically refers to Coolant Thermostat. Whenever this code comes up, you should immediately pay attention to the problem that’s causing it and fix it right away.

P0128 Code introduction
Component got P0128 Code

However, it’s not very strict about forcing you to find the solution immediately, and there is usually come a time you can drive before you go on to fix it.

So, in this article, we will look at how long you can drive your car after the P0128 code comes up and how significant it is. Let’s start without wasting any further time.

What Does P0128 Mean?

What Does P0128 Mean
Introduce P0128 code

Before we actually dive into any of the details, you should have prior knowledge as to what P0128 really means and how it is so important. Without knowing this, you couldn’t really get its significance.

P0128 code essentially means that the coolant of the car engine is not getting warm enough as fast as it is supposed to be.

This leads to us believing that there is something wrong with the engine temperature operating system, which is why it is keeping the temperature to reach that level.

There is a module especially installed in the vehicle whose job is to track the time it takes for the engine to reach the operational temperature, called PCM.

PCM order the fuel to enter into the loop once the temperature inside the engine is over a certain number. Normally the time is 15 minutes after the engine starts or when the temperature is above 160 Fahrenheit.

However, once the said temperature is achieved by the car engine, the temperature has to keep going down until it gets under 160F while the engine is running.

This way, the PCM keeps recording data and keeps checking whether the time the car is taking is normal or if the car is taking more time and behaving abnormally.

In case of abnormal operation, the PCM will trigger the P0128 code to appear and let the driver know that something is up, and the car’s engine is not getting heated up as expected.

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Causes of P0128

Causes of P0128
P0128 Code reason

So now that we know what does P0128 really means, we have an idea of what is going on whenever the PCM triggers the P0128 code. Now let’s look at what could be the possible reasons why it could happen.

There are actually four main causes of the activation of the P0128 code. It could be any of the following cases.

1. Stuck open coolant thermostat

If the thermostat is left open for quite a long time, it could definitely record in wrong readings of the temperature, and this wrong data getting fed in could mess things up and force the PCM to trigger the P0128 code.

2. Missing thermostat

The thermostat not being present could also easily cause the code being going off as there is no coolant present now, so the temperature doesn’t have a reason to come down.

3. Faulty coolant temperature sensor

Faulty coolant temperature sensor
Coolant temperature sensor

Well, if the temperature sensor of the coolant is giving out wrong readings due to the sensor going bad, it could definitely cause the PCM to take into account inaccurate values based on which it could trigger the code.

4. Radiator Fan

Without the radiator fan, the temperature sometimes goes way up above expectations as there is nothing cooling down the engine, so obviously, the temperature of the engine is messed up, which is followed by the P0128 code showing up.

5. Faulty wiring or coolant circuit

The wiring of the coolant circuits could keep it from working, and as a result, the engine won’t cool down, causing the engine temperature to hike. This ultimately forces the PCM to trigger the P0128 code.

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Symptoms of P128 Code

Symptoms of P128 Code
P128 Code Symptoms

Well, you really cannot do anything about something going wrong if you are not able to detect it in the first place.

So, even if you know a lot about P0128 and know its solution as well, both are of no use if you are not able to diagnose it first.

So, below listed are some of the signs which will let you know about the P0128 coming up.

1. Engine Start uptime

Well, probably the most anticipated one, the vehicle will take a lot more time than usual for it to warm up. The change will be noticeable, and you will know that there is something wrong.

2. High idle

The idle is usually higher than normal most of the time.

3. Temperature Gauge

As compared to the usual circumstances, the temperature gauge mostly stays at lower levels, and only rarely it goes up; however, it stays low most of the time.

4. Fuel Economy

As the engine takes more than usual time to heat up, the fuel economy will also have a setback. This will cause your fuel to run out more often than it used to be, and you will have to refuel more often.

5. Engine Light

Probably the easiest one to discover, the engine light will go on reminding you that the engine is not completely normal, and there is something wrong up with it.

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Is It Safe to Drive With P0128 Code?

Is It Safe to Drive With P0128 Code
Driving while P0128 Code

Well, now we come to the real deal. The most asked question when it comes to this topic asked by people is how long shouldn’t they worry when driving around with a P0128 code.

As now you have pretty much the basic knowledge of all aspects of P0128, its meaning, what causes it, and how to discover it, let’s see if it’s safe to drive with it or not.

Well, to be very straightforward, it is not very dangerous to drive with a P0128 code as suggested by some people. As you might guess, it only takes more time to reach the temperature, but eventually, it does.

However, this never means that it is completely safe to drive with the code as well. Your engine heats up less quickly than usual, so you should always have an eye out for engine heat up.

Especially if you are going out for a long journey, pay attention to the magnitude of the problem before going off, as the engine heats up quite more than usual during longer journeys.

How Long Can You Drive with A P0128 Code?

How Long Can You Drive with A P0128 Code
Driving limitation with P0128 Code

Well, now that we know it’s not totally dangerous to travel with a P0128 code, the next question that pops into one’s mind is how long we can actually drive before fixing it? Let’s see

As much as P0128 does not pose a huge threat, which means it doesn’t need you to respond to it immediately, you shouldn’t either ignore it for such a long time that it starts to become a big problem.

The more time you take fixing the problem, the greater the risk it becomes for the health of your engine. It is eventually leading to a dead-end.

In case of not fixing for a long time, it could even lead you to the contamination of the oil and water inside the engine, which obviously makes a problem for engine health.

So, since you can easily drive your vehicle with a P0128 code, you should not want to do it for a long period of time.

You can spend the maintenance until you take time out for a check-up and can even delay it by driving for around a thousand miles, which is frankly much.

However, waiting for a time more than 1000 miles could make things serious, and the results are not guaranteed to be in your favor in such a case.

And even if you do manage to keep it running over 1000 miles as well, there is always a great risk posed by it to the engine, and trust me, engine repairs don’t come cheap.

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Final Thoughts

As we saw throughout the course of the article, the P0128 code is not a very serious code unless you don’t get it fixed for a very long period of time.

Before going for about 500 miles after the code comes up, there is no immediate reason to get it fixed as it won’t leave you stranded on the side of the road.

However, it is recommended to get it fixed after about 1000 miles as, after that distance, things could become serious, and it could affect the health of your engine.

There are many ways which you could follow in order to diagnose if there is a problem with your P0128, so you know there’s something wrong.

Moreover, the reasons for the code coming up are also discussed, so you know why did it happen at first and could prevent it from happening in the future as well.

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