I have a 2007 jeep compass...it stalled the other day. I took it to auto zone for a code reading...states code U1403. What is this and how can I fix it?
"U-codes" (codes beginning with a "U" prefix) are communications faults. Your vehicle is equipped with several computer modules which are all networked to gether on what is called the "Control Area Network" or "CAN". When one of the modules failes to communicate or if there is invalid data being transmitted by one of the modules, a U-code is stored in continuous memory in one or more of the other modules.
In your case, U1403 pertains to invalid or implausible data being recieved from the fuel level sensor by the Powertrain Control Module. Please note that this is NOT a fuel level sensor failure code and does NOT indicate faulty fuel level sensor circuits.
Theory of Operation
The TIPM receives a fuel level signal over CAN B from the Cluster. The TIPM transmits the fuel level message to the PCM over the CAN C bus.
The possible causes of this code are: > Open or shorted CAN B circuit > Instrument Cluster (CCN) > Totally Integrated Power Module (TIPM) > Powertrain Control Module (PCM)
To properly diagnose tis code, you must use a scan tool to access and verify data on all available modules. You must also determine if this is an active fault or an intermittent fault.
I don't see a fuel level signal problem at the PCM causing your engine to stall. However, the fuel level signal may be getting lost or "scrambled" due to a lack of communications between modules or a malfunctioning module. This could cause all sorts of problems (including stalling).
I would also like to add that my personal experience with this type of problem (communications faults) has taught me that the FIRST thing that should be done is a THOROUGH check of the BATTERY and CHARGING SYSTEM before attempting any communications diagnostics. If your battery is more than 4 years old, it is VERY LIKELY be the ROOT CAUSE of the problem. Computers tend to do all kinds of wierd things when they are not being fed properly.
Answers & Comments
"U-codes" (codes beginning with a "U" prefix) are communications faults. Your vehicle is equipped with several computer modules which are all networked to gether on what is called the "Control Area Network" or "CAN". When one of the modules failes to communicate or if there is invalid data being transmitted by one of the modules, a U-code is stored in continuous memory in one or more of the other modules.
In your case, U1403 pertains to invalid or implausible data being recieved from the fuel level sensor by the Powertrain Control Module. Please note that this is NOT a fuel level sensor failure code and does NOT indicate faulty fuel level sensor circuits.
Theory of Operation
The TIPM receives a fuel level signal over CAN B from the Cluster. The TIPM transmits the fuel level message to the PCM over the CAN C bus.
The possible causes of this code are:
> Open or shorted CAN B circuit
> Instrument Cluster (CCN)
> Totally Integrated Power Module (TIPM)
> Powertrain Control Module (PCM)
To properly diagnose tis code, you must use a scan tool to access and verify data on all available modules. You must also determine if this is an active fault or an intermittent fault.
I don't see a fuel level signal problem at the PCM causing your engine to stall. However, the fuel level signal may be getting lost or "scrambled" due to a lack of communications between modules or a malfunctioning module. This could cause all sorts of problems (including stalling).
I would also like to add that my personal experience with this type of problem (communications faults) has taught me that the FIRST thing that should be done is a THOROUGH check of the BATTERY and CHARGING SYSTEM before attempting any communications diagnostics. If your battery is more than 4 years old, it is VERY LIKELY be the ROOT CAUSE of the problem. Computers tend to do all kinds of wierd things when they are not being fed properly.