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P0800 is a diagnostic trouble code (DTC) for "Transfer Case Control System (MIL Request)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Transfer Case Control System (MIL Request)
P0800 is an OBD-II generic code that the engine control module (ECM) got an input from the transfer case control module (TCCM) to turn on the malfunction indicator light (MIL).
This code is only used by the TCCM to activate the MIL through the ECM. The TCCM has to be accessed separately to diagnose additional codes.
The TCCM has a malfunction in one of the transfer case sensors or circuits and would set an internal separate fault code for the failure other than code P0800.
The cause of code P0800 is only a pass through code to the ECM from the TCCM notifying it has a fault in the TCCM.
Code P0800 is set by other manufacturer specific codes for transfer case problems. Not all manufacturers use code P0800 unless the TCCM is not on the vehicle's module network with the ECM.
The Check Engine Light will be illuminated and the code is set in ECM memory as a TCCM fault request to turn on the MIL.
The transfer case may have unknown issues since code P0800 is only an informational code and not the true fault code stored in the TCCM.
Scans codes and documents the code in the ECM.
Scans for codes other than P0800 in the TCCM and diagnoses those codes as per the manufacturer's pinpoint test.
Clears the ECM and TCCM code P0800 after repairs are done for any other TCCM code.
Checks the catalyst and sensor for any signs of damage or leaking joints in the exhaust.
Since code P0800 only means that the TCCM has detected a fault in its system, the severity of the fault will depend on the codes that are existing on the TCCM.
The Check Engine Light being on causes the vehicle to fail emissions testing.
The TCCM may have serious problems that code P0800 only directs the mechanic to do further checks in the TCCM for other codes to diagnose.
Code P0800 is only an informational code sent from the TCCM to the ECM to tell if there is a problem in the transfer case and to check the TCCM for detail codes it has set in the TCCM memory.
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