Problem Solved! 2.4ltr U0401

We have a 2015 4x4 Jeep Chrysler Dodge Patriot with the 2.4ltr / 2.4l engine and it took months to finally figure out what was wrong because the issue was sporadic until it wasn't. The first few months we where able to get the car going again by resetting the check engine light and it would be fine again for weeks or even months. The whole time we would always get a U0401 Code. The U0401 code stands for “Invalid Data Received from ECM/PCM 'A'”, which means modules on the data network are receiving implausible data from the vehicle's powertrain control module. The common causes of the U0401 code include one or more faulty sensors, a dead battery, and data network issues. Due to it being so easy to get the car going again we decided to not start throwing parts and the car until it really became an issue. The day of this car being dead in the water was inevitable but it took 6 months before this day would come. In the end the car was giving us a non responsive gas pedal, high idle (1500 rpms) and a clicking from the throttle body at shut down and start up. The car was able to be nursed back to my garage by driving it at a maximum of 10-15 mph and putting the car into neutral at stop lights.
This video shows you a step by step how to on replacing the TB and position sensor on this 2.4 liter engine. It is a tight fit to get to the bolts. This youtube video should give you a look at what you'll end up doing by feel. I've done worse auto repairs but you'll end up with a few hand cramps in the end.
Here is how to diagnose and repair U 0401 -
Perform a preliminary inspection
Sometimes U0401 can pop up intermittently, or it can result from a dead battery. This is especially true if the code is a history code and not current. Clear the code and see if it returns. If it does, the next step is to perform a visual inspection. A trained eye can check for issues such as broken wires and loose connections. If a problem is found, the issue should be repaired and the code cleared. If nothing is discovered, check for technical service bulletins (TSBs). TSBs are recommended diagnostic and repair procedures put out by the vehicle manufacturer. Finding a related TSB can greatly reduce diagnostic time.
Check the battery
The ECM needs proper voltage to operate. Before doing anything else, the battery and charging system should be checked for proper operation and repaired as needed. Then, clear the codes and see if they return.
Check for other DTCs
Additional diagnostic trouble codes (DTCs) may indicate problems elsewhere that are affecting ECM operation. For example, multiple communication DTCs may indicate a problem with the CAN network. Any additional DTCs should be addressed prior to diagnosing U0401.
In the case where multiple communication DTCs are stored, diagnosis will shift to the CAN bus. Like any other electrical circuit, the bus can be checked for problems such as opens and shorts. Bus testing typically starts at the data link connector, either with a digital multimeter (DMM) or a breakout box. Pin 6 of the datalink connector is CAN High, whereas pin 14 is CAN low. If a problem is detected, further testing and repair of the CAN bus can be competed as needed.
Check for a faulty control module
If U0401 is the only DTC stored, the ECM module itself should be checked. The easiest was to start this process is by attempting to communicate with the ECM using a diagnostic scan tool. Once connected to the vehicle, the tool acts like just another module on the network. It can be used to address the ECM module. If the module does not respond, there is a problem with it.
Before condemning the module, it's important to check its circuit. Like any other electronic device, the ECM module must have proper power and ground. This can be checked using a DMM.
If the module's circuit it good, yet it still won't communicate, it is likely faulty. Before replacing the module, however, its software should be checked. Often times a module can be reprogrammed instead of replaced.
Timestamps:
0:00 Hearing Clicks
0:17 Into - Meet the vehicle in needing repaired & symptom's
1:08 Why this is a common failure on these cars
1:27 Location of the part in question
1:40 Start of the repair job / removing air cleaner and battery
2:30 Removing the throttle body 13mm and 10mm needed
4:55 New part costs and unboxing - Buying local Vs. online
6:00 New part installation
9:05 Air Box and Battery Install
10:53 Test Run and Clearing Old Codes
Other diagnostic codes related to U0401
All the 'U' codes are network communication codes. Codes U0100 to U0300 are lost communication with XX module codes.
2007-17 Caliber, Sebring, Patriot, and compass, 2009-2024 journey 2008-14 avenger and of course 2011 to 2014 Chrysler 200
More OBD-II U Codes you may encounter
U0400
U0336
U0335
U0334
U0333
U0332
U0331
U0330
U0329
U0328
U0327
U0326
U0402
U0403
U0404
U0405
U0406
U0407
U0408
U0409
U040A
U040B
U040C
U040D

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