How to Troubleshoot and Fix the P1491 Jeep DTC Code?

Unlike any other trouble code, DTC P1491 is considered moderately severe to severe. It suggests that there is a problem with the radiator fan relay. 

As a result, if you delay taking the necessary action, your engine could overheat and cause further issues.

No worries, we will discuss every bit of detail to troubleshoot the code and to get your Jeep back on the road. Keep reading to find out more!

What Does the P1491 Jeep Code Mean?

The diagnostic trouble code (DTC) P1491 indicates issues with your Jeep’s radiator fan relay circuit. 

When the check engine light comes on, and you get the code with the OBD-II scanner, you’ll notice “Radiator Fan Relay Circuit Condition. ” 

The radiator fan for any Jeep model plays a vital role in cooling the engine, therefore as soon as the code is stored, you must take the necessary steps.. Now, let’s break down the diagnostic trouble code into some pieces.

  • P = Powertrain Control Module
  • 1 = A generic manufacturer-specific code derived from the SAE standard.
  • 4 = Additional systems for emission reduction.
  • 91 = Specific fault code 00-99 ( Here, the fault code indicated issues with the radiator fan relay on your Jeep)

P1491 Code: What Causes Radiator Fan Relay Circuit Condition on Jeep?

As we mentioned before, code P0419 describes something bad with the radiator fan relay. Make reasons for which the component to malfunction.

But in most cases, the issues are related to the radiator fan relay rather than to other major components in Jeep.

The other possible reasons include the following:

  1. Radiator fan blown fuse.
  2. The radiator fan relay shorted the wiring harness.
  3. Radiator fan relay in poor electrical condition.
  4. Bad temperature sensor.
  5. Faulty radiator fan relay.
  6. Malfunctioning radiator fan.
  7. Bad powertrain control module (PCM).

We have made the list of the possible causes in such an order which makes a lot of sense about how you should troubleshoot the code.

Read Also: How to Troubleshoot & Fix P0507 Jeep Grand Cherokee Code?

How to Troubleshoot and Fix the P1491 Jeep Code?

To solve the issue we need to find the root cause of it and the best way to solve it. Here, we will guide you on checking, analyzing, and finally fixing the code. 

In some instances, you require professional assistance, whereas in others, addressing the root cause only requires a fundamental understanding of how the affected components function.

1. Check and Replace the Blown Fuse of the Radiator Fan

Let’s start with checking the tiny fuse. The radiator fan fuse plays a decent role by contributing to the engine cooling procedure on your Jeep. 

And, a radiator fan fuse’s core responsibility is to protect the fan relay circuit. 

If there are any issues with the fuse like a blown fuse, it can cause the radiator fan relay not to work. 

And when the radiator fan relay is unable to work, it can’t receive a signal from the powertrain control module of your Jeep and operate the radiator fan.  

In such a situation, your Jeep’s computer thinks there is an issue with the radiator fan relay, and that’s why you get to discover the code. 

The radiator fan fuse is located on the fuse box of your Jeep. What you need to do is to access the fuse and check whether it is shorted. 

If you find the fuse in a shorter or damaged condition, you should replace it. Replacing the radiator fan relay blown fuse can cost $20-$50 without labor costs.

Read Also: How to Troubleshoot and Fix U1120 Jeep DTC Code?

2. Check and Replace the Shorted Wiring Harness of the Radiator Fan Relay

Next, Have you ever wondered how the radiator fan in your Jeep receives a signal from the powertrain control module and uses this engine temperature signal to run the radiator fan? 

Through the wiring harness. The wiring harness connected to the powertrain control module and radiator can ensure the smooth performance of the radiator fan.

Now if the wiring harness of the radiator can relay is shorted to damaged, the important component is not supposed to function properly. 

Many issues can cause the radiator fan relay wiring harness to be shorted. Excessive wear and tear, cut-out wiring, electrical overload, and moisture are the most prominent reasons behind the issue.

Therefore, the first thing you need to do is visually inspect the wiring harness of the radiator fan relay. 

And if you find the component in a shorted or open condition, there is no alternative to replace it. But in such a case, we recommend you go with the mechanic to resolve the issue better. 

3. Check and Fix the Radiator Fan Relay’s Poor Electrical Connection

If the wiring is ok, check the electrical connection. The radiator fan relay on your Jeep needs enough electrical power to perform its operation. 

Usually, the issue of the radiator fan relay’s poor electrical connection emerges due to loose wiring harnesses. 

And when the radiator fan relay wiring harness becomes loose, it can’t get electrical power from the battery and can function properly. 

And it makes sense that a poor electrical connection in the radiator fan relay can’t direct the fan when to turn on and when to turn off. ECM considers this situation the worst, and the check engine light turns on. 

Engine overheating is the worst thing that can happen if the radiator fan doesn’t run. So, the best thing you can do here is to check the connection of the radiator fan relay

Now if the electrical connection is not satisfying enough or is poor due to a loose wiring harness, you need to tighten the wiring harness and fix the issue. 

And in such a case, it will also be helpful for you to go with the mechanic as soon as possible.

Read Also: How to Troubleshoot and Fix the P0457 Jeep DTC Code?

4. Check and Replace the Bad Temperature Sensor

Due to the bad temperature sensor, the radiator fan relay can’t work compared to what it is supposed to do. The temperature sensor’s key role is to let your Jeep’s powertrain control module know the engine’s temperature.

If the engine’s temperature is too high, the powertrain control module sends the signal to the radiator fan relay. 

Then the radiator fan relay directs the radiator fan to turn on. But if the temperature sensor malfunctions, there is nothing to do with the radiator fan relay.

Solutions? You should check the temperature sensor of your Jeep. If the temperature sensor is bad, you are supposed to face the issue of engine overheating. 

If the tempera sensor looks damaged or worn out, you need to replace it rather than repair it as soon as possible. And it might cost you $300-$350.

5. Check Repair/Replace Faulty Radiator Fan Relay

Let’s say you have performed all the steps one by one mentioned above. But doing all the previous troubleshooting methods can not fix the issue. 

In that case, you need to check the radiator fan relay for any further damage. Yes, it might happen that the radiator fan relay malfunctioned and caused the code P1491 in your Jeep.

When the radiator fan relay is bad, it can’t get the engine temperature signal or data and then runs the radiator fan according to that. 

And if this happens, your Jeep’s computer thinks your Jeep is in bad condition. Therefore, you are more likely to deal with the diagnostic trouble code P1491. 

The solution to this cause is simple! You should check the radiator fan relay and replace it if broken, damaged, or worn out. 

But if the radiator fan relay is full of dirt and debris and results in corrosion, cleaning the component properly will do the job for you. It will cost you around $60-$70.

Read Also: How to Troubleshoot P1281 Jeep Grand Cherokee DTC Code?

6. Check and Replace the Malfunctioning Radiator Fan

Unsurprisingly, a malfunctioning radiator fan often causes the issue of code 01491. 

So, if you can’t figure out the code even after checking the radiator fan relay, extreme chances are the radiator fan itself goes bad. 

The biggest way to be sure about whether the radiator fan goes bad is engine overheating. 

What exactly can happen due to a bad or faulty radiator fan? If the radiator fan is broken, worn-out, or clogged and loses functionality, the engine’s lack of coolant supply becomes overheated quickly. 

Coolant leakage in the engine can cause the radiator fan to malfunction. So you need to check whether the radiator fan looks bad. To be more precise, check whether the radiator fan runs properly. 

But unfortunately, if the radiator fan, which is located between the radiator and the engine, goes bad, you should replace it. Ready to pay approximately $700-$800.

7. Check and Replace the Powertrain Control Module

The last thing you must do is check the PCM. There is less chance that the powertrain control module of your Jeep can cause the P1491 code. But chances are there. 

Why? As the code P1491 indicates issues with the radiator fan relay, this can happen if the powertrain control can’t get data from the engine temperature sensor of your Jeep. 

And it becomes impossible for the radiator fan relay to get engine temperature sensor data from the powertrain control module and direct the radiator fan. However, you must be careful regarding replacing the powertrain control module.

Make sure you know the right scenario of when to replace it and how. Replacing the powertrain control module will cost you $600-$800.

Read Also: How to Troubleshoot & Fix P0132 Jeep DTC Code? (Ultimate Guide)

Frequently Asked Questions

In different corners of the internet, we’ve seen how Jeep owners react regarding the P1491 Jeep code. So, in this section, we have listed a few common questions to answer.

Can you drive a Jeep with a P1491 code?

In an emergency, you’ll be able to drive your car with the code P1491. But according to the opinion of experts, it is not recommended to drive your car as the code can cause engine overheating. 

How much does it cost to fix the Jeep P1491 code?

The cost to fix the issue of code P1491 on your Jeep depends on what component causes the code to occur. However, it might cost you around $60-$1000. However, it is better to discuss the cost with the mechanic. 

How can code P1491 cause the Engine to overheat?

To understand this, you must dive into the code’s depth. The code indicates something wrong with the radiator fan relay circuit; if it malfunctions, it can’t operate the radiator fan properly, which will cause engine overheating.

Final Thoughts

If you take proper care of your Jeep, you can avoid the diagnostic trouble code. Once you are dealing with the P1491 Jeep code, do troubleshooting step by step to get the root cause and solve it.

Do you have prior knowledge about Jeep repair? If not, go with the mechanic.

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