P0691 code — how to fix error fast

There are some OBD2 codes like P0691 that could turn out to be much worse than they seem if the driver doesn’t take them seriously. This one is among the common problem codes related to the engine’s performance, and most drivers don’t realize why that’s the case.

In this guide, our team will give you some of the basics of P0691 code meaning, what causes it, and ways of fixing it. We’ll also do what we can to explain what you can do to prevent the code from re-emerging, so let’s do it.

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What does the P0691 code mean?

The P0691 code refers to a problem in the fuel pump control module (FPCM). This module controls the fuel pump relay, which is responsible for supplying fuel to the engine. When the control module detects an issue, it will store the P0691 code in the vehicle’s computer system and trigger the check engine light.

If this code is not addressed promptly, it can lead to serious consequences for your vehicle’s performance. A malfunctioning fuel pump can cause the engine to stall, refuse to start, or even lead to a breakdown on the road.

Symptoms of the code include poor fuel efficiency, a lack of power, and difficulty starting the engine. If you notice any of these symptoms, it’s important to have your vehicle diagnosed as soon as possible.

What causes the P0691 code?

Regardless of the code being related to the malfunction of the fuel pump itself, there are several other reasons that could consequently lead to this issue. We decided to give you an overview of all the potential triggers of the code.

Faulty fuel pump control module

A faulty fuel pump control module can cause the fuel pump relay to malfunction, leading to the P0691 code. This can occur due to corrosion, damage, or a short circuit.

Wiring issues

Faulty wiring or loose connections in the fuel pump control module circuit are also among the most common causes of the P0691 code. It could happen due to damage or age-related wear and tear.

Failed fuel pump relay

A failed fuel pump relay can also trigger this code. This can occur due to a damaged or worn relay, or a faulty connection between the relay and the FPCM.

Failed fuel pump

Finally, a failed fuel pump can cause the code if the fuel filter gets clogged or if there’s low fuel pressure. The pump can simply wear off as well and in this case, it leads to the code being displayed.

Which car models does the P0691 code affect the most?

While the P0691 code can appear in any vehicle, certain car models are more prone to this issue. We went in pursuit for the details on such vehicles that might be exposed, so here’s what we’ve found out:

• Honda Civic: Some Honda Civic models have had issues with their ECMs, which can trigger this one and other related codes. The problem has been attributed to faulty soldering in the ECM circuit board
• Chevy Cobalt: Certain model years of the Chevrolet Cobalt have experienced issues with the ECM/PCM relay control circuit, resulting in the code being activated. In some cases, the issue may be caused by a damaged or corroded relay connector.
• Dodge Ram: Some Dodge Ram trucks have had problems with their ECMs, leading to DTC P0691 and other codes. The cause of the issue is not always clear, but it may be related to wiring or grounding problems.

How to diagnose the P0691 code

If your vehicle is displaying the P0691 code, it’s important to have it diagnosed by a qualified mechanic. They will use specialized tools and equipment to perform a comprehensive diagnostic check of your vehicle’s fuel system.

However, there are some steps you can take yourself to try and diagnose the issue at hand before you get your car to a mechanic, so here are the steps to follow:

Check the fuel system for damage

The first step in diagnosing the code is typically a visual inspection of the vehicle’s wiring, connectors, and related components. This can help identify any obvious signs of damage or wear that may be contributing to the problem.

Test the fuel pump relay

After visually inspecting the fuel pump, you can check the voltage of the fuel pump relay since a power loss could have caused the pump to malfunction. You can use a diagnostic tool to test the relay and replace it if the faulty relay is the cause of the issue.

Check the fuel pressure

Finally, you can also have a mechanic check the fuel pressure of your vehicle since it could give you some more tips on what’s causing the problem with this code.

How to fix the P0691 code

To truly fix the code without leaving any chance for it to come back on, you’ll need to fix the component causing the issue. That’s why we went over the diagnostic methods to help you figure it out, and now we’ll go over the solutions:

Repair damaged wiring or connections

If the issue is related to damaged wiring or connectors, you may need to repair or replace these components to address the problem.

Make sure to check the electrical connections related to the fuel pump control module since these can often be the underlying culprit of the code.

Fix or replace a fuel pump

If the fuel pump itself is the problem, it will need to be replaced. This can be a costly repair, with prices ranging from $500 to $1500 depending on the make and model of your vehicle.

Repair the fuel pump control module

Finally, the one last solution you can try is to check the fuel pump control module and do some software updates if needed or replace it. In case it wears off, it’s important to change the module as soon as possible to make the fuel pump run according to the manufacturer’s specifications.

How to prevent the P0691 code

While there is no foolproof way to prevent the P0691 code from occurring, there are steps you can take to reduce the risk of a fuel system failure. Regular maintenance and inspections of your vehicle’s fuel system can help identify potential issues before they become major problems.

Some preventative measures you can take include:

• Regularly replacing the fuel filter according to the manufacturer’s recommended schedule
• Keeping your gas tank at least a quarter full to avoid running the fuel pump dry
• Having regular inspections of the fuel system, including the fuel pump, fuel pump control module, and wiring connections

By following these preventative measures and addressing any issues promptly, you can help keep your vehicle running smoothly and avoid the code.

Our take

As it turns out, the code P0691 can get pretty messy if you don’t deal with it ASAP since it could lead to a lack of fuel being injected into the engine.

We hope that you’ll have an easier time figuring things out now after reading our guide, and don’t forget to properly maintain your vehicle to prevent the code from re-appearing.