Scan Test is Incomplete P1000 Repair

The computer system or PCM (powertrain control module) that controls your car is equipped with a basic operating program. This operating program is designed to control your engine, transmission, emissions, safety systems and more. If a scan has been performed by using a code scanner and a "scan could not be completed" code is retrieved further troubleshooting is necessary. Usually a trouble code P1000 or manufacturers equivalent. We have listed several reasons for this condition.

Step 1 - Stuck Engine Thermostat - If the engine thermostat has stuck open it forces the engine coolant to stay at too low of a temperature causing the computer to stay in open loop. This open loop creates a state of pre-programmed parameters were no diagnostic tests can be preformed. The computer is constantly waiting for the engine to heat up to operating temperature for closed loop operation.

Step 2 - Shorted Sensors - The computer relies on information from the oxygen, mass air flow, throttle position, crankshaft position and coolant sensors to operated, if one of these sensors is severely shorted it can cause the computer to stay in open loop, causing a code gathering incomplete trouble code.

Step 3 - Shorted Fuel Injector - If a fuel injector short circuits it can cause the engine not to run by shorting the injector driver. If the car doesn't run and a code gathering incomplete trouble code like P1000 is present, it could be a fuel injector shorted. Unplug all injectors and rescan the system.

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Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-10-25)