Search
Close this search box.
Search
Close this search box.

5 Ford F150 PCM Failure Symptoms To Know Of

Ford F150 2005 engine bay with the PCM highlighted and circled

Your Ford F150 has a mind of its own called a PCM (Powertrain Control Module) – This module manages the engine and transmission as well as the various sensors throughout the vehicle. However, like any other component of your vehicle, it can and will break down over time. When that happens, your truck will start showing several signs that indicate the severity of the problem.

While a typical Ford F150 can have numerous performance and diagnostic symptoms as its PCM fails, the following 5 are the more common ones:

  • Check engine light
  • Problems with startup
  • Significantly reduced gas mileage
  • Failed emissions test
  • Engine stutter

While these signs do warn of imminent PCM failure, they may also indicate other problems. Therefore, by reading further, you will learn how to interpret these signs and ways to troubleshoot them.

5 Common Symptoms of Ford 150 PCM Failure

While it is no KITT from the 1980s TV show Knight Rider, your Ford F150 has a sophisticated computer brain under the hood. Called the Powertrain Control Module (PCM), it manages and controls everything inside your truck. Some systems report directly to it. Though, most of the time, it is through subsystems such as Engine Control (ECM) and Transmission Control (TCM). (Jasper, 2022)

Some important functions your F150’s PCM manages include:

  • Engine and transmission
  • Airflow between the engine and exhaust
  • Coolant temperature
  • Speedometer, tire health, and acceleration
  • Fuel injection and spark plugs

Because it controls so much, Ford F150 PCM failures can lead to serious problems. First and foremost, those failures sever the communication between the PCM and the other modules, causing multiple systems to break simultaneously. This scenario can obscure the true cause of those issues, leading to costly diagnostics and repairs.

Luckily, there are a few noticeable signs that point directly to a PCM failure, especially if they occur together. While ideally, you want an expert technician to examine and identify the problem, noticing these symptoms can help you and your technician rule out other potential causes, saving you time and money in the process.

Ford F150 2004-2008 PCM isolated against a white background
Ford F150 2004-2008 PCM (Powertrain Control Module)

1. Check If the Engine Indicator Lights Up

Your Ford F150’s dashboard indicator lights serve as your initial warning that something is amiss under the hood. This is especially true for the Check Engine indicator. It serves as the “catch-all” warning for your engine and transmission. As such, the indicator is not a sufficient sign of a PCM failure on its own. However, it is a warning that the PCM detected an issue somewhere. (Jasper, 2022)

Therefore, you should take your F150 in for a full diagnostics test. Such a test will discover the location of the system malfunction so the technician can repair it if necessary. It would also let your vehicle pass most state vehicle inspections.

2. The F150 Is Sluggish to Start or Will Not Start

Besides the warning lights, a sluggish ignition is another significant sign that something is wrong with your pickup truck’s PCM systems.

Fortunately, the problem is usually with the ECM system, such as:

  • Unbalanced fuel-to-air ratio
  • Damaged spark plugs or harness
  • Irregular engine timing
  • Weak battery

These problems can cause ignition issues or prevent the vehicle from starting together. As such, you must take your vehicle for repairs immediately.

Luckily, the problem should be quick and cheap to fix. Except for some extreme cases, the rest of your truck’s components should be fine. The PCM is normally just a sensor and a warning system in these situations. As such, it is likely performing its tasks flawlessly.

However, these issues can break the PCM and engine if left unchecked. Therefore, you should seek professional help before you end up stranded in the middle of nowhere in inclement weather. If your truck stops completely, it is already too late.

3. Low Gas Mileage

Your F150’s PCM decides how much fuel streams through your engine as well as the right gear for the terrain. It computes these things using sensors in the ECM and TCM systems. Any failure in these functions will deteriorate your gas mileage.

Without appropriate instructions from the PCM, the engine may fail to receive the right fuel-to-air mixture. When that happens, it will start acting erratically. It can jerk or stall. It may even speed up to overcompensate for the lack of a turbo boost, consuming more fuel in the process. Either way, the situation can lead to permanent damage as the process can erode the oil and other lubricants.

Therefore, if your F150’s fuel economy drops significantly, you should have the PCM checked. However, a bad PCM is not the only issue that can cause low mileage. It could be anything from a bad air filter to a deflated tire. As such, you may want to rule these other causes out before going for a more expensive repair job.

4. Emissions Test Failure

If the PCM fails, and your engine errs with an extremely fuel-rich fuel-to-air ratio, some of the gasoline will fail to combust completely and remain in the exhaust. It may even produce more carbon monoxide as well. This rich exhaust can create strong foul-smelling and oddly colored smoke. 

When this happens, your Ford pickup truck is most likely to fail its emission tests, but that is the least of your worries. If not repaired, the condition can ruin the engine’s performance. Given the high costs required to replace an engine, you want to address the issue as soon as possible.

Fortunately, if your problem is a failed PCM system, the fix should be simple and inexpensive. These modules are mostly plug-and-play and should be easy for a trained technician to replace or reset. As such, you should always check the PCM first if your truck fails a test.

5. Engine Stutters or Stalls

We mentioned it before in passing, but a stalled or stuttering engine is a major indicator of a failed Ford F150 PCM system. That is because the problem is normally caused by improper engine timing and the PCM holds your vehicle’s internal clock. As a result, a broken PCM can break other components such as the engine.

However, a bad PCM is not the only possible cause, just the most likely one. (Martynyuk, 2022) It could also be a mechanical problem such as bad ignition coils. However, like the other issues in this list, a failed PCM is your best and cheapest option to replace and repair.

Therefore, you should have the PCM checked first. This is especially true if your Ford has other symptoms as well.

Other Common Symptom

The above symptoms are the most common ones that the average Ford F150 owner can see. However, they are not the only ways a faulty PCM will reveal itself. As such, we included some of the more obscure ways below.

Ford F150 2004-2008 instrument cluster isolated against a dark grey background with the check engine light circled
Ford F-150 2004-2008 Instrument Cluster Panel

While not immediately obvious to an owner, these are often the better indicators:

  • Irregular or Random Shifting – This happens due to a faulty sensor or water damage in either the PCM or TCM. Can damage transmission if not repaired quickly. Can lead to collisions on the road.
  • PCM-Related Error Codes – Direct and most obvious sign of a faulty PCM. Must retrieve through an external OBD2 reader device. The first thing you should check is if you suspect a bad PCM. Most PCM failure codes start with “P06”, such as P0606, P0603, and P0113, with the full list available online.
  • OBD2 Scan Device Cannot Connect – OBD2-compliant diagnostic devices use plug-and-play technology to link your reader to your vehicle’s PCM. Therefore, if it cannot make such a connection, it is an immediate sign that something is wrong with the PCM system. (Ahmed, 2022)
  • Voltage Overload – An unusually high voltage reading from the vehicle’s electrical system is a good sign of a shortage in either the actuator circuit or solenoid. These shorts can destroy the delicate electronics in the PCM. 
  • Water damage and other Environmental Factors – If your engine block shows signs of water damage or other weather-related issues, you should have the PCM checked. Water can short out and damage extremely advanced computer components.
Auto mechanic providing diagnostic by scanning the car for codes via OBDII port with the scan tool visible

What Triggers the Ford F150 PCM Failure Symptoms?

Ford F150 PCM failures can happen in numerous ways.

But the most common ones are:

  • Vibrations
  • Corrosion
  • Short circuits
  • Overheating
  • Voltage overloads
  • Manufacturing Defects

These environmental factors can damage any electrical system. So, you should expect to see the failure symptoms mentioned above if you notice any of them on your vehicle. This is especially true after a heavy rainstorm.

Water can quickly render any PCM useless. It can seep into the housing to corrode the electrical contacts, severing any connections to the PCM. It can also create shorts across sensitive components, leaving them damaged in the process. The issue is so bad that more mechanics will not fix flooded vehicles.

The 2004-2008 Ford F-150 and Lincoln Mark LT PCMs are particularly prone to failure. Not only are the 5.4L 3-Valve V-8 engines poorly designed but there are circuit board design flaws inside the PCM that result in component failure. These PCMs can be repaired or replaced. If you’re replacing the PCM it’ll need to be programmed to the VIN of your truck first.

If you’re getting P0351-P0356 codes there’s a good chance that the failure is inside the PCM. Repairing your original is typically the path I’d recommend since it’s original to your car so after it’s been repaired it won’t need to be re-programmed.

There are independent repair shops like UpFix that will repair your PCM. You would need to remove it from your vehicle and mail it to them. Make sure the codes and issues are something that can be traced to the PCM first before sending it out.

What to Do If You Witness Ford F150 PCM Failure Symptoms?

If you discover that your Ford features one of the above signs of a PCM failure, you should not panic. More often than not, a PCM failure is not a problem with the PCM itself. Instead, the issue is normally a faulty sensor, shorted wire, or a bad auxiliary system. However, you should never ignore the sign. (Hopper, 2022)

Your best bet will always be to take your pickup to a professional, Ford-certified pickup truck mechanic. They should have all the required diagnostic and repair tools to find and solve any issues your Ford may have. Although, you can check the various online PCM repair guides if you are suitably mechanically inclined.

Either way, the solutions for repairing a faulty PCM are the same:

  1. Physically Test and inspect Your PCM, the wires, and the battery. Check for rust and worn-out or frayed connections. Also, ensure the battery is fully charged
  2. Scan for OBD2 error codes. Use an OBD2-compliant diagnostic scan tool to check the error codes if your PCM passes the physical inspection.
  3. Update the PCM if firmware updates are available. These updates may fix the issue without having to replace the whole unit.
  4. Reset the Ford F150 PCM. If the above procedures fixed the issue, you must rest the PCM, or it may falsely report the same issues again
  5. Replace the PCM if nothing works. you can rebuild it, swap it out with a working compatible used model, or buy a new unit.
Ford F-150 2004-2008 red pickup truck in Quintana Roo, Mexico

Average Ford F150 PCM Replacement and Reprogramming Cost

The cost of a PCM can vary from as low as $90 for mainstream vehicles to as much as a few thousand dollars for luxury models.

The Ford F150 sits in the middle of the range, setting you back $500 to $1500 just for a new PCM unit. You can also expect to pay around $120 for hourly labor charges from most independent auto-electricians. (Jasper, 2022)

If the price for a new PCM is out of your budget, you can try to find a refurbished or used unit for a few hundred dollars from a junkyard. However, you must reprogram the unit before you can use it in your Ford. Luckily, PCM reprogramming is a lot cheaper than buying a new unit. You can typically expect to pay around $80 to $150 for it including labor. Reprogramming can take up to a half hour though.

Frequently Asked Questions (FAQ)

Q: How Do You Reset the PCM On a Ford F150?

A: You disconnect the battery for 20 minutes. The PCM will reset itself after you reconnect the battery.

Q: What Problems Can a Bad PCM Cause?

A: A bad PCM can prevent your F150 from starting up while degrading the crankshaft.

Q: Can a Car Run Without a PCM?

A: Your Ford F150 will not run without a PCM if it has an automatic transmission.

Q: Where Is the PCM On a Ford F150?

A: Your Ford’s PCM is under the dashboard behind the passenger side kick panel. However, some recent models moved the unit to either the driver’s kick panel or the engine bay mounted on the firewall.

Conclusion

The PCM in a Ford F150 serves as the brain for the vehicle, managing how it runs and operates. However, it can break down like any other component. When it does, it leaves its mark by altering the vehicle’s performance. If you see any of these symptoms, your best bet is to repair the issue right away.

Your subscription could not be saved. Please try again.
Thanks for subscribing, see your free e-book on your inbox!

References:

Car Wizard

Auto Guide Guy

UpFix

Ford F150 (2004-2008) PCM Computer Repair

Cars-Care

Ford F150 Pcm Failure Symptoms

Cars Flow

Ford F150 PCM Failure Symptoms – 7 Top Reasons Explained

Motor Hills

Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

Leave a Comment