PCM Reprogram Due To Engine Shudder 21N08

image of Ford logo with words superimposed" Ford PCM Reprogram Due To Engine Shudder"

The F150 is the best-selling pickup truck in America and has been for 45 years. The Ford F150  sold 663,508 trucks in 2021, beating out Ram and GM. Because they are such a popular model, Ford F150 owners have their own forums and subreddits devoted to their truck model. This makes it easy for them to compare symptoms, find solutions and unlock the best-hidden features in their trucks. 

There are several F150s, Expeditions, and Navigators that needed a PCM reprogram due to an Engine shudder. These effected models include: 

  • F150 2017-2020 model years
  • Expedition 2018-2020 model years
  • Navigator 2018-2020 model years

This vehicle repair also covers the Ford Raptor and Limited F150 variants. 

If you previously received the 21B10 PCM update at a Ford dealer and are now experiencing the engine shudder, you should take advantage of the PCM reprogram. Be aware that your cam phaser rattle may return. You may then need the cam phasers replaced through the 21N03 customer satisfaction plan.

What Causes This Engine Shudder?

closeup of ford raptor engine bay under the hood

Originally, I understood the engine shudder to be a miscommunication between the camshaft position sensor and the PCM. I’m getting a better understanding on this, now.

The previous 21B10 customer satisfaction update was designed to send more oil to the cam phasers. This resolves the cam phaser noise on startup issue (you know, the annoying Ford cold start cam phaser rattle). More importantly, this recall is supposed to help extend the life of the cam phasers as demonstrated by their extended warranty coverage for vehicles that received this PCM reprogram prior to February 2022.

However, the increased oil in the cam phasers may affect engine performance, especially when cruising at a steady speed. The affected vehicle exhibits a very noticeable shudder, and can be pretty concerning.

Ford’s brilliant idea was to revert the programming back to the original level. This removes the shudder. I imagine that you may get the cold start rattle and earlier cam phaser failure, but at least the engine won’t shudder.

Oftentimes, this engine shudder may be mistaken for a transmission shudder. Any shop with an IDS scan tool will be able to check your car for transmission codes.

Program Details

image of technician with a laptop reprogramming a car's computer aka PCM

Ford is offering a no-cost repair to reprogram the PCM on these vehicles suffering from engine shudder following the previous 21B10 update. This repair is a one-time thing and is only offered until Janurary 1st, 2023.

The Powertrain Control Module (PCM) needs to have been first reprogrammed under the earlier customer satisfaction program 21B10. This new customer satisfaction program is designed to reverse engine shudder caused by this previous PCM calibration.

Customer Satisfaction Program 21B10 was an extended warranty coverage on engine cam phasers on vehicles that had received a PCM reflash prior to December 31, 2021. The 21B10 was designed to solve a cam phasers rattle by increasing oil flow to them, but a percentage of affected vehicles demonstrated the side effect of an engine shudder. 

The initial cam phasers rattle would generally first appear on a cold start due to a lack of oil. Unfortunately, many users reported a return of the symptoms after the 21B10 reflash. Ford then released two further customer satisfaction programs as an extension of coverage. These are named 21N03 which is targeted to the startup rattle and replaces the cam phasers. The 21N08 is a pcm reprogram due to engine shudder that reverts the programming back to the original programming prior to the 21B10 reflash.

This newer field service action 21N08 software update is designed to solve the motor shuddering problem caused by the 21B10 reflash. This generally only affects a low percentage of vehicles that received the 21B10 flash. However, the engine shudder is quite noticeable.

Summary of Related Cam Phaser Rattle Recalls:

  • 21B10 – PCM reprogram to stop cam phaser rattle by pushing more oil to the cam phasers
  • 21N08 – PCM reprogram to stop engine shudder by reverting vehicles back to original settings prior to the PCM update provided in the 21B10 reflash.
  • 21N03 – Cam phaser replacement as a one time repair on certain vehicles with 3.5L GDTI engine with undesirable rattle on startup.

Should You Buy Or Avoid These Vehicles?

images of gray ford f150 models on dealership lot

If you are an astute shopper, you might have found these issues before buying a vehicle. Sometimes you can get a Ford for cheap because it has a cold start rattle. If you know how to fix it cheaply, then you might be able to get yourself a deal.

We cover this rattle in detail and how to fix it for free.

First off, be aware that CarFax may show these recalls whether or not they have been done. So you need to verify with your dealership with your VIN that the recall repairs have been done. If not, you will want to get the latest computer updates before the warranty expires on it. 

So far, these recalls have been effective at solving the problem and improving customer satisfaction.

Generally, Ford’s are extremely reliable vehicles and are cheap to repair. Since we know what these issues are, you are safe to buy one of these Ford models. At the worst, if the issue re-appears (low likelihood), you might end up out of pocket for a fairly affordable repair. 

Even with these known issues, the Ford F150 has an annual maintenance cost estimate of about $858 per year.

If the Carfax shows that the vehicle that you are looking at buying has already received the 21B10, then you may need to take it in for the 21NO8 reflash to revert those settings. 

How Much Does Cam Phaser Replacement Out Of Warranty Cost?

Source: Ford Boss Me

Because the 21B10 has expired and the 21N03 is about to expire at the time of this writing, we need to explore what your costs would be if you needed to replace the cam phasers out of your own wallet. 

Cam phaser requires extensive effort and should only be attempted by those who are comfortable with working on cars. Your car should also be outside of its warranty in order to keep from voiding a warranty on your car. 

Here is a quick overview of the repair:

Source: DMI INC

Symptoms of a bad cam phaser include a loud engine rattle or tick when the engine is running, a check engine light, and stalling at a red light. In some cases, the engine may enter limp mode.

Cam Phaser replacements costs at least $1200, depending on the shop. Generally, the timing chain, chain tensioners and water pump will be replaced at the same time, driving costs up to about $3,000. The good news is that replacing the cam phasers will fix the cold start rattle. 

How Much Does A Powertrain Control Module Reflash Cost?

It is difficult for me to get a price right now on the PCM reprogramming since it is still under warranty for a few more weeks, so most front-desk service advisors don’t have pricing. That said, after some pressuring, I had a Ford technician told me that it would likely cost around $300 to run the reprogramming on your PCM if you were to bring it in outside of warranty. I’ll try to update this report in 2023 as this customer satisfaction bulletin expires.

Owner Letters

Recall letters were mailed to each affected vehicle owner On September 27, 2021. 

Adaptive Shift Warning

Ford’s are equipped with an adaptive shift feature where the computer learns to adjust the shifting for a smoother ride based on the driver’s habits. When the computer is programmed, it will erase this programming and the vehicle will have to relearn your driving habits. There may be some less smooth shifting during this process.

Zachary Drumm

Hey! My name is Zachary Drumm! This site allows me to test new tools, piddle around in the garage, and share the insights I get from flipping cars and houses. When it comes to tools, home improvement, and being a “shade tree mechanic,” you’ve come to the right spot. If I’m not in the garage creating content, you’ll find me outside, running, canoeing, and traveling. My goal is to empower more people to be self-sufficient.

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