How To Fix Fault Code 1246 On Cummins Generator (Error Solved!)


The fault code 1246 on Cummins power generators is one of those problems that are not operator serviceable.

Modern power generators, such as the ones made by Cummins, are very complex machines.

Because of this, there are some issues that can crop up which users are not able to or shouldn’t even attempt to fix on their own.

Having a reliable source of electrical power is the reason why someone would have a backup power generator, and any problem that can happen with it or its engine should be fixed as soon as possible so it could perform its duty.

But sometimes, you as an owner of a generator might have a very limited number of options for what you can do in a given situation.

If you are dealing with fault code 1246 on your Cummins generator, please continue reading to find what it is and what you can do to fix it.

What is Fault Code 1246 on Cummins Generator

Your backup generator is the thing that supplies you with electricity when the supply from the grid fails you for any reason.

That’s why you have it after all, for when it is needed. And when it shuts down and throws an error code at you it is very important to get down on it and remove the cause of such fault code.

But sometimes it is not as simple as that.

Cummins has a system of classification of the fault codes for their power generator, divided into five categories:

  • Category A codes are those that are related to faults of the engine or alternator and which render the generator non-operational, and these faults must be repaired by a trained technician;
  • Category B codes are for faults that are degrading generators’ performance or can lead to damage to the engine or alternator, the generator is not non-operational but it is advised to keep it running only for critical applications. These faults should be fixed by trained technicians;
  • Category C codes are for those faults that do not impact generators’ performance but can mean defects of the engine sensors thus leaving it without any protection. These faults also require that a trained technician corrects them. In the case of running the generator while one of these codes is active, any problem with the generator that arises will not be covered by your warranty.
  • Category D codes are for faults that can be relatively easily fixed by the operator.
  • Category E codes are various non-critical faults and warnings, mostly related to improper user settings and operations.

Fault code 1246, unfortunately, falls in the category C group and means that the generator’s control unit has received some unspecified error code from the engine’s ECM.

While there are many error codes that ECM can send to PCC, and that are mapped in PCC’s software because of their function, not all are.

The error code 1246 arises whenever PCC receives one of these unmapped error codes from ECM.

Read also: How To Fix Fault Code 1434 On Cummins Generator

Reading the Fault Code on Cummins Generator

Reading fault codes on Cummins generators equipped with PowerCommand control units is very easy, especially for those that cause a shutdown of the generator.

All you need to do is to press the STOP button and it will show up on the LCD screen.

First, the shutdown status LED will be lighted up by the red color, the one with a pictogram that looks like an upside bulb and is crossed by two X-shaped lines.

Then the LCD display will show the message saying, depending on the exact model of your generator:

  • Fault Number 1246: CAN UNKNOWN ENGINE FAULT


  • Fault Number  1246: GENERIC ENGINE FAULT

In case that you see one of these messages, your generator’s PCC has received the information from the engine’s ECM about some error and needs to shut it down.

But if you see some other message, then you are dealing with a different situation and a different problem.

The exact problem will be signaled by that particular fault code, for which you can find information on how to fix it on other pages of this blog.

Read also: How To Fix Fault Code 1433 On Cummins Generator

Troubleshooting fault code 1246

The fault code 1246 means that the generator has shut down due to some unspecified engine fault. Because of this, to troubleshoot this problem you would need some specialized equipment.

This is also the reason why it is highly not recommended to attempt it by yourself and leave the fixing to properly trained and certified technicians.

Neither the required hardware, besides a PC or laptop with RS232 serial bus connector or USB type-A port, nor software needed for diagnostic is readily available to the general public.

Namely, you would need an InPower harness A044M377 with the RS485 to RS232 serial port converter, and an RS232 serial port to USB type-A port converter, preferably the Brainbox PN A053T968, in case that your PC/Laptop does not have an RS232 serial port

When it comes to software, you would need EControls’ ECM display software, depending on the exact model of your generator most likely the 4G Display suit, version 391 or newer.

But even if you had all this equipment, you should be aware that you will void the warranty on your generator if you attempt to diagnose or repair this engine fault, even in the case that you are able to get your hands on replacement parts.

Technically, it is possible in this situation to jump-start the engine of your generator, though it is highly not advised to do so.

The best-case scenario is that your generator’s engine will be running with a faulty sensor, while chances for something to go wrong, which should trip any engine sensor are rather small, they are not nonexistent.

In such conditions, you are risking that something goes wrong with the engine which is unable to detect and prevent escalation of some potential problems.

And if something does go wrong, Cummins will not accept your warranty.

Prevent Fault Code 1246 from Reoccurring

The fault code 1246 is related to the functioning of the engine and engine’s sensors. Thus preventing this situation from ever arising means following all of the recommended procedures for maintenance and operating your backup power generator.

Regularly checking the coolant and oil levels, removing any debris from air intakes and radiator and intercooler, if your generator is equipped with a turbocharged engine.

In its own right, this fault code is not very likely to happen ever, but sometimes it can.

Generally speaking, it most likely happens due to a faulty engine sensor, of which there are many.

Though Cummins generator engines are equipped with high-quality sensors, that should last a considerable part of the generator’s life span, they can break.

Either from manufacturing defects and sheer bad luck or because it is not possible that they last as long as the engine or generator.

In the simplest terms, these things just can happen, and in the best-case scenario, with the proper maintenance of the generator’s engine, you could hope to postpone it by some.

Unfortunately, these types of problems are completely unpredictable and cannot be foreseen.

On the other hand, they occur relatively seldom, and if they ever happen you can rest at ease that very likely you have seen the last of it.

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Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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