How to Fix P0628 Code On Cummins? (Complete Solutions)

If you’re a Cummins Truck driver and have spent your fair share of time on the road, you’ve already dealt with several DTCs – Diagnostic Trouble Codes. Though it can give you tough times, it’s necessary to help you find out the trouble with your car and how to fix them.

The Code P0628 on Cummins is detected when the voltage is low at the fuel or lift pump circuit ‘A.’ There are many reasons that can lead to this trouble code, but it mostly happens when the control circuit opens up due to any reason.

If you’re facing this trouble code on your Cummins, you need to get your head steady first because this comprehensive guide will cover all the aspects of Code P0628 and the solutions to the problems, including the costs.

P0628 Code On Cummins

What Does P0628 Code Mean On Cummins?

The code P0628 is a generic transmission code on Cummins vehicles or trucks. This particular code refers to the low voltage of the fuel lift pump.

The fuel lift pump plays a pivotal role in driving the engine of your Cummins. No fuel will reach your engine without the lift pump or fuel pump. According to the operator’s command, the control circuit turns the fuel pump on and off.

However, if the circuit opens, it’ll cause the code P0628, and your Cummins will start showing a few systems immediately. Here’s the breakdown of Code P0628:

  • P = Powertrain, the system that moves your vehicle forward.
  • 0 = SAE Generic Code.
  • 6 = Computer Auxiliary Output.
  • 28 = Specific fault sign (In this case, the control circuit opens up)

How Serious Is P0628 Code On Cummins?

When it comes to the severity of the problem, this particular code is moderately severe trouble for your car or vehicle. You can continue using your vehicle with this trouble code. But the Cummins engine performance won’t be the same.

If the control circuit opens up and causes this trouble code, your engine won’t get fuel. Without fuel, you can’t drive your car for long. It may also keep shutting off on the road.

However, it is better to avoid driving this way because this can put your life at risk. Your engine may start mixing fuels inside, which can do some severe engine damage henceforth.

What Causes P0628 Code On Cummins?

Though many reasons can cause Code P0628 on Cummins, we’ve already shown you the open control circuit is a major one. Now, let’s move on to the other causes of trouble code P0628 as follows:

  • Fuel pump issue
  • A faulty or damaged bus CAN
  • The device’s control module has severed ground wire.
  • High circuit resistance
  • Corroded or melted connectors
  • Open and shorted CAN bus wiring
  • Internal corrosion wire
  • A broken circuit caused by unsecured wires and harness
  • Control module’s unattached ground strap

How To Fix P0628 Code On Cummins?

We should warn you that fixing the P0628 Code is quite difficult. It is better to leave the job to the professionals. But if you’ve experienced automobiles, you can follow our guidelines to fix this trouble code on Cummins.

As with other automobiles, you’ll require an OBD-II code reader to diagnose trouble code P0628 on your Cummins. Once you’re done with the diagnosis, you can proceed with the following troubleshooting steps:

Step 1: Scan and Test

As mentioned above, you need to use an OBD-II code reader to diagnose the trouble code. Still, after diagnosis, you need to scan and test every Cummins module immediately using the same scanner. You must inspect the wiring and connectors visually.

Step 2: Examining the Ground Circuits

When dealing with fuel pump module components, you must also examine the ground circuits. You can use a separate ground of battery to do this. You can make this happen by attaching an auxiliary ground cable at times.

You should inspect the ground circuits thoroughly to find any pins, corroded connections, terminals, etc. When you find them out, immediately repair or replace them.

Step 3: Identifying the Circuit

You’ve already found out the cause of P0628 is an open circuit, so you should try to identify the circuit thereof. You can use the wiring diagram for your electrical service manual and identify the circuit.

Once you identify the circuit, you can easily trace the fuel pump individually. Then you can check if there is any break or leak in the wire. When you find one, try repairing it if possible.

Step 4: Replacement

But in case the wires are beyond repair, you should better replace them with a new one. Circuit wires are available for an affordable price so that they won’t cost you much.

But it’ll give your engine circuit a new life and start showing that in no time. We highly recommend replacing parts because only then does the control circuit function in optimum condition.

Step 5: Checking Control Module

Your Cummins should get fixed already without this step. But if it doesn’t, you may need to get your circuit control module of Cummins checked by a professional.

This is a tricky job, and therefore a single wrong step can ruin all the efforts. Therefore, consult an expert and let him check your circuit module out.

Other Symptoms Of Getting P0628 Code On Cummins

When the trouble code P0628 appears on Cummins, it’ll start showing immediate reactions like the engine not starting or the engine keeps shutting off. Apart from these two symptoms, some other symptoms are as follows:

  • Illuminated check engine light
  • Reduce fuel economy
  • Stalling engine
  • Misfires
  • Engine cranking is okay but not the starting
  • When the engine reaches the operating stage, it dies.

How Much Does It Cost To Fix Cummins P0628 Code?

It’ll take an hour of work to fix trouble code P0628 by a professional. Now, the cost varies from place to place because of the hourly work rate of the experts. But most professionals charge their labor rates according to the diagnosis and fixing the time of an automobile repair.

They often charge a few bucks extra due to the model or engine type of vehicle. But most automobile repairing places charge from $75 to $150 per hour. So, you can get your Cummins trouble code P0628 fixed within this cost.

Can You Drive Your Cummins With Code P0628?

Though we don’t recommend driving with trouble code P0628, you can move your Cummins with it. When the fuel pump voltage stays low, it is because of the open circuit. And therefore, the fuel won’t reach your Cummins engine.

Your Cummins engine won’t start often, or it may keep shutting off on the road without fuel. This will certainly put you a risk, so we don’t recommend you drive your Cummins with the P0628 code.


Whether searching for the basics to understand the p0628 trouble code or getting accurate information to fix this trouble on your Cummins, hopefully, this article has delivered it to you.

As a car owner or a driver, you can save money on repairs by finding out the problem in the initial stage and fixing it before it worsens.

If you’ve no experience fixing this type of issue, consult a professional immediately. It’ll cost you less in both cases ag the problem initially.

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