P0605 Code: What It Is And How To Fix It

Over 86% of the systems on today’s vehicles integrate electronics and computer controls. Most people don’t realize how powerful the modern automotive Powertrain Control Module (PCM) really is. Today’s cars have more computing power than what was equipped on the spacecraft that put man on the moon. In fact, they’ve had more power than the Apollo 11 space shuttle for around the past three decades.

One of the last things you want to hear is that your vehicle’s computer module is failing and, unfortunately, that may be the case if your vehicle has set the P0605 fault code.

What Does The P0605 Error Code Mean?

The PCM, also referred to as the powertrain control module, uses a “checksum” verification strategy that will detect if there are issues between the communication of the microcontrollers and the output drivers. If the PCM’s checksum detects a communication error, the P0605 error code will be set. In simple terms, the vehicle’s computer will perform a self-test to detect internal computer failures. If an internal failure is detected during the self-test, an error code will be set. Because the P0605 code is generic, it may be set by any manufacturer such as Nissan, Kia, Hyundai, and Ford.

Since your vehicle’s computer controls many of your vehicle’s systems, like fuel, ignition, traction control, cruise control, and Advanced Driver Alert System (ADAS), to name a few, it figures that a faulty PCM can cause numerous issues.

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What Causes The P0605 Error Code?

Fortunately, there are only a few issues that could cause the P0605 error code, such as:

• Resistance in PCM connections
• Water intrusion in connectors or PCM
• Low voltage supply to PCM
• Poor ground to PCM
• Faulty PCM

Symptoms Of The P0605 Error Code

The following symptoms can be experienced with the P0605 error code present:

• Cylinder misfires
• Extended cranking
• Inability to start the vehicle
• Inoperative systems, such as the radio or instrument cluster
• Engine stalling
• Illuminated check engine light

Can I Drive My Car With This Issue?

Whether you can continue driving the vehicle will depend on your make/model. In some cases, the vehicle will remain operable; in other instances, the vehicle may not even start or stay running.

If your vehicle feels normal, you can continue driving it. If your vehicle exhibits serious performance issues like stalling or cylinder misfires, we recommend repairing it as soon as possible.

How To Fix A P0605 Error Code On Your Vehicle

Before any repairs are made, we always recommend you have your vehicle’s computer scanned to verify the error code is active. You can have your computer scanned by a local parts store or auto repair facility. Typically, the auto parts stores will perform a scan, whereas the repair shops may charge up to $150.

Unfortunately, the most commonly reported fix for the P0605 code is to replace the PCM. This may not be the case with your vehicle, as poor connections and corrosion can also be the culprit. Additionally, there are times when a PCM reflash can remedy the issue. We recommend checking for warranty enhancements, service campaigns, recalls, and technical service bulletins before paying for a PCM replacement.

Connector Inspection

We recommend inspecting PCM connections before paying to replace the module. Often, you’ll find water from a clogged evaporator drain or sunroof drain causing corrosion or water intrusion on the connectors. Even a spilled drink has been found to cause this. Always find and fix the cause of water intrusion.

PCMs are typically located behind the glovebox, passenger-side kick panel, or in the engine bay. Simply disconnect the connectors to inspect them. If corrosion is found, light amounts of electrical contact cleaner can be used to attempt to remove corrosion. We recommend using Stabilant 22, which is a contact enhancer to ensure proper connection.

PCM / Module Replacement

Depending on your vehicle, you may be able to replace the PCM yourself using a replacement product from Dorman or FlagshipOne. These companies offer pre-programmed replacement modules that do not require programming, VIN writing, or updates. If you’re attempting to do it yourself, this is the way to go.

Some of the steps to replace a PCM include:

1. Disconnecting the negative battery cable
2. Disconnecting the PCM connectors
3. Unbolting the PCM
4. Replacing the PCM
5. Reconnecting connectors and negative battery cable

How Much Does It Cost To Fix?

Like most other repairs, depending on the exact fault and model of your vehicle, the cost to fix the P0605 error code will vary. Warranty enhancements, recalls, service campaigns, and some technical service bulletins may lead to a free or low-cost repair.

Replacing a PCM is rarely cheap, but lately, aftermarket companies have been coming to the aid of many customers with affordable replacements. Vehicles change rapidly these days, so it’s not uncommon to find that the manufacturer is no longer making replacement modules for your vehicle. A factory replacement PCM for a Kia Sorento can cost almost $1,400 just for the part alone when not on sale or discounted.

If you are choosing to have a shop or dealership replace your PCM, which may be the only option depending on your vehicle, expect to pay for additional labor costs. Sometimes, programming a PCM can take well over an hour plus labor time to physically replace the module. RepairPal estimates an average PCM replacement will cost around $1,000, but we’ve seen this number climb well past $2,000 for the module alone, not including labor.

The P0605 error code is one you don’t want to see. Your PCM is not a component you’d want to completely fail. With the help of some aftermarket companies, you can save some money, so if your vehicle is setting the P0605 error code, you’ll want to get it taken care of sooner rather than later.

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