|Code||Fault Location||Probable Cause|
|U2011|| Module Transmitted Invalid Data (Non SCP) |
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What Does Code U2011 Mean?
OBD II fault code U2011 is a generic trouble code that is defined as, “Module Transmitted Invalid Data (Non-SCP)”, and is set when the PCM (Powertrain Control Module) or any other capable control module detects incorrect data being transmitted between control modules over a serial communications system that does not follow the J1850 aka Standard Corporate Protocol (SCP) communications protocol.
Limited space precludes a comprehensive discussion on automotive communication protocols, but to keep things simple, we can explain the main differences between Standard Corporate Protocols and non-Standard Corporate Protocols- at least as far as the cheap generic code readers that most non-professional mechanics own are concerned. It should be noted, however, that since the technical details of the two classes of communications protocols fall outside an article such as this, we will only provide a general overview of this topic. Let us start with-
Standard Corporate Protocol (SCP)
“Standard Corporate Protocol” is the name carmaker Ford gave to a communications protocol that conformed to the J1850 standard, which is the standard all communications protocols have to follow to allow generic scan tools to communicate with a vehicle’s OBD II system. In some ways, the acronym “SCP” became a kind of non-official standard for all communications protocols that were based on Ford’s interpretation of the J1850 standard, regardless of the vehicle that was using the protocol.
The SCP protocol used a serial bus that was made up of two twisted wires that operated in the 0 to 5 volts range, and terminated on pins 2 and 10 in the standardized data link connector. In practice, the SCP protocol was the most common communication link between the PCM and the transmission control module, but when the SCP protocol was largely replaced by Medium and High Speed CAN (Controller Area Network) communications systems by around 2006, many more (additional) vehicle control systems and modules operated on the SCP protocol.
Note that this protocol was not only the most common communications protocol on Ford products: it was also the most common protocol used in related makes, including Jaguar, Lincoln, Mercury, and others.
Briefly, non-Standard Corporate Protocols include (among others) the UART Based Protocol (UBP), FlexRay, as well as the various variants of the ubiquitous CAN (Controller Area Network) bus systems. In practice, all modern vehicles use both Low Speed, Medium Speed, and High Speed Can bus systems as well as other systems and protocols in various combinations.
For instance, a High Speed Can system will link control modules that monitor and control critical functions like the ABS and several Advanced Driver Assist Systems, while Medium Speed CAN bus systems will link control modules that monitor and control systems such as active suspension control, traction control, and stability control. In practice, which control modules are linked by which communications system depends on equipment and systems fitted to the vehicle, but in all cases, High Speed CAN communications enjoy precedence over any other category of communications, thus preventing conflicts between various classes of control modules.
As a practical matter, both Medium Speed and High Speed CAN systems use 2 wires for redundancy and both employ 0-1 volt signals using a 2.5-volt bias. Each protocol has “+” and “-” circuits. Medium Speed CAN “+” and High Speed CAN “+”+ cycle from 2.5 to 3.5 volts, while Medium Speed SCAN “- “ and High Speed CAN “-“ cycle from 2.5 to 1.5 Volts. Moreover, vehicles that use a Medium Speed CAN system but it is not connected to the data link connector, those vehicles use specialized gateway modules that convert Medium Speed CAN communications to High Speed CAN communications.
In terms of operating principles, each control module on any given non-SCP communications system is programmed to both identify itself when it transmits data and to only recognize data transmitted to it from control modules that are authorized to communicate with it. Thus, in a fully functional non-SCP communications system, all associated control modules will collect input data from sensors and other monitoring devices process that data, and then share the processed data among themselves, and it is here that things can get difficult.
Since data shared among control modules is transmitted in strictly formatted and controlled formats, any one or more control modules on that system recognize when data is invalid, inaccurate, implausible, or missing, because each control module is programmed to expect certain data from other control modules both in a set format and at fixed intervals. Thus, when any given control module on a non-SCP communications network detects invalid data being transmitted from any other associated control module, the receiving control module(s) will a) acknowledge the invalid data, and b), set a fault code to alert one or more “parent” modules that a fault had occurred somewhere in the system, which brings us to-
The problem with code U2011
From a diagnostic perspective, the presence of a trouble code like U2011 -“Module Transmitted Invalid Data (Non-SCP)” is of little to no help in identifying the cause of the problem. There are a great many other trouble codes that relate to failures, defects, or malfunctions in non-SCP communications systems, but in all cases, the most valuable diagnostic information such codes contain is the fact that something had failed in a CAN bus system, as opposed to something having failed in a non-CAN bus system.
See the section on “Causes” for more details on possible/probable/likely causes of code U2011.
Where is the U2011 sensor located?
This image shows an example of a typical crankshaft position sensor (arrowed), which could conceivably generate inaccurate or invalid data when it (or the reluctor wheel that works in conjunction with the sensor) malfunctions or fails.
Other possible, and perhaps more likely, examples of defective equipment that could cause code U2011 to set include0
- defective wheel speed sensors
- ADAS (Advanced Driver Assist Systems) cameras, sensors, microphones, and radar/lidar transponders
- body control modules
- transmission control modules
- gear selector switches
- engine coolant, intake air sensors, and transmission fluid temperature sensors
WARNING: Note that we do not recommend that non-professional attempt to diagnose and repair code U2011 and/or any other UXXXX code because this level of diagnostics requires specialized equipment and expert-level knowledge of the affected vehicle to prevent causing possible fatal damage to the vehicle’s electrical system.
What are the common causes of code U2011?
The possible root causes of code U2011 cover a lot of ground, so to speak, but since code U2011 does not identify the communication system in which the failure had occurred, possible causes could include one or more of the following not only in the system that had reported the fault but in almost any other communications system that is associated with the affected system-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or electrical connectors anywhere in the affected (or related) system-
- Defective sensor(s) almost anywhere in the affected (or related) system
- One or more defective control modules
- Corrupted or damaged software/programming in one or more implicated control modules
- The use of incompatible software and/or calibration versions when control modules are replaced or reprogrammed
- Incomplete on incorrect programming procedures when control modules are replaced or reprogrammed- especially when some ADAS (Advanced Driver Assist Systems) is programmed or calibrated
- Defects in the charging system that cause abnormally high or low system voltages
- Disconnecting the battery to “clear” other fault codes
What are the symptoms of code U2011?
Due to the large number of possible causes of code U2011, it is impossible to provide even a partial list of likely symptoms of code U2011 here. However, by noting symptoms like-
- drivability issues
- increased fuel consumption
- loss of power
- rough running and/or poor idling
- the conditions under which the engine stalls, hesitates, or stumbles
- the quality and predictability of gearshifts
- which warning lights are on and whether (or not, as the case may be) illuminated warning lights are flashing or burning steadily
- whether the engine is difficult to start
- whether the vehicle is in a limp mode
– it is (sometimes) possible to narrow the list down somewhat. However, bear in mind that since code U2011 involves a failure or malfunction in a CAN bus system, it might not be possible to access non-global OBD II fault data with generic scan tools. Global information is diagnostic information that relates to emissions, i.e., engine and fuel management data, which should be accessible to all medium and high-end generic tools.
However, interpreting global diagnostic data can sometimes be challenging even for professional mechanics, so we strongly recommend that you seek professional assistance with the diagnosis and repair of code U2011, or any other UXXXX trouble codes to avoid causing serious, if not always fatal damage to the affected vehicle’s electrical system.