What Does P1689 Code Mean and How To Fix?

In the automobile industry, certain codes are used to indicate different types of problems. The codes vary depending on the variety of problems. P1689 is one of those trouble codes. 

This trouble code happened due to problems with the Fuel Pump Control Module (FPCM) and Powertrain Control Module (PCM). The P1689 problem arises for some reason whether it is automatic or a mistake made by you. 

When the P1689 trouble code appears on your vehicle, you will notice certain symptoms. You can get rid of the travel code by following a few proper steps. 

In this article, we will learn more about code P1689 and how to fix this problem.

What Does P1689 Code Mean?

The Diagnostic Trouble Code (DTC) P1689 means that there is no proper communication between your vehicle’s Fuel Pump Control Module (FPCM) and Powertrain Control Module (PCM). 

The job of an FPCM is to control the voltage at your vehicle’s fuel pump. By controlling the voltage, the FPCM maintains the fuel pressure throughout the entire operating range and the fuel supply to the engine. 

On the other hand, the job of a PCM is to collect data from all the sensors in a vehicle and maintain the engine, fuel delivery, emission functions, ignition timing, etc. properly. The PCM of a vehicle is called its brain.

When your vehicle’s FPCM doesn’t work properly, the PCM sends you a P1689 warning on the dashboard.

Symptoms Of Getting The P1689 Code

When the P1689 trouble code appears on your vehicle, you may notice many specific symptoms. Below are some notable symptoms of the error code:

  • Check Engine Lights is on;
  • Sometimes you can hear a disturbing sound in the back of the vehicle;
  • The vehicle is not accelerating when the gas pedal is pressed;
  • The engine is stalling when the accelerator is pressed;
  • Gas mileage decreased;
  • The gas pressure seems to be low because there is not enough gas flowing in the engine.

The Causing Factors Of The Error Code P1689

Whether it is automatic or a mistake you made, the P1689 code appears on your vehicle for certain reasons. The following are some of the notable causes of this trouble code:

  • Problem with the FPCM: If there is an error in the FPCM of your truck then the P1689 travel code can be identified. Symptoms that may occur in this case are engine stalling, engine not starting, no sound coming from the fuel pump, etc.
  • Open or shorted FPCM Harness: In some cases, the FPCM harness of your truck may be loosened or shortened. In this case, PCM does not get an accurate reading from FPCM. That’s why PCM shows the P1689 travel code on your dashboard.
  • Open or shorted FPCM Connection: In some cases, your truck’s FPCM connection may be opened or shorted. Then FPCM cannot work properly. So PCM does not get any information from FPCM. That’s why PCM displays the P1689 travel code on your dashboard.

How Serious Is Code P1689?

The P1689 trouble code must be taken seriously as it interferes with the smooth running of your engine. Since PCM monitors your truck’s FPCM functions all the time, ignoring the P1689 code can cause PCM problems that can be detrimental to your entire truck. 

On the other hand, your truck can’t run without these two model systems. The worst thing is that if either PCM or FPCM is damaged, it will cost a lot to replace it.

How To Solve P1689 Error Code?

OK, now is the time to find out how to solve the P1689 error code. Since we already know the symptoms of that code, we will now know some possible solutions in light of them.

If There Is Any Error in FPCM-

There may be a problem with the FPCM of your truck. Such as a sensor may be damaged or the entire module may be damaged. If the problem is minor then maybe a skilled mechanic can solve your problem. 

However, if there is a major problem, it may be that you have to replace the entire FPC module. The most difficult thing to replace is its cost.

If There Is a Problem With the FPCM Harness-

The most common problems with a truck’s FPCM harness are wiring and connectors. Either the harness’s wiring or connection is loosened or they are shorted. Therefore, before replacing the harness completely, these things should be carefully observed. 

If any of the harness connections are loose or open, re-plug them. On the other hand, if a connector or wiring is short, replace it.

If There Is An Error in the FPCM Electronic Connection-

Just because your truck’s FPCM is damaged does not mean that the PCM will not get the correct reading. Sometimes there can be problems with the electronic connection of the FPCM due to unavoidable reasons. For example, the connection may open or loosen on its own or there may be a wiring short. 

So before replacing a major by spending a lot of money, all these details should be observed. Sometimes minor repairs can save you a lot of money. 

If any electronic connection to your truck’s FPCM is loose or open, re-plug it and replace it completely if it is shorted.

How Much Does It Cost To Solve The Error Code P1689?

The cost of repairing the P1689 trouble code will depend on which method you are using. Your costs may vary depending on the location and the different repair shops. In most cases, however, the repairing costs range from 75 to 150 dollars.

Common Mistakes While Solving The P1689 Code

If you try to fix the P1689 trouble code, you will encounter some common mistakes. The first of these is that you may forget to change the engine oil thinking it is a serious problem. Sometimes that trouble code can be solved just by changing the engine oil.

Again in many cases, the common mistake is not being able to diagnose fuel pollution accurately. Some mechanics do not make that observation and replace your truck’s battery. But the truth is that battery replacement has little to do with the P1689 error code unless the matter is major.

Additional Comments To Consider Regarding The P1689 Code

Several issues came up as additional comments on the P1689 error code. As-

  • Always try to use good and authorized fuel. 
  • Never run your vehicle on a small amount of fuel. The result is pressure on the engine which is detrimental to it. 
  • Change the fuel filter at least two to four times a year. 
  • Clean your fuel tank regularly.


Finally, we can assure you one thing that you can gain detailed knowledge about the above P1689 error code if you read the discussion well. By adding practicality with this knowledge you can easily fix the P1689 trouble code of your truck. 

But always keep in mind that if you find yourself having trouble fixing any kind of error code, be sure to call a skilled professional.

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