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2009 2.2L Pontiac G5 Comes up code P0641 What does this mean? Thank you

Driving, engine light comes on, then the dash says reduced power. I slowed down because my engine felt like I was skipping a plug. I pulled over, shut off engine for a while, checked my oil and other liquids. Manual transmission. Drove home slow. Diagnostic came up P0641. What does this mean? Thank you

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Po641 on a 09 g5 2.2 means that there is a problem with the 5 volt coming from the ecm the same 5 volts is sent to about 6 sensors you need to look at the 5 volt referance pid on a scan tool and disconect the sensors one by one till the referance volts comes to about 5 volts if that don't work then check the wires for a short to ground , usually ther are other codes in the memory to give you a hint

Posted on Feb 15, 2012


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SOURCE: my service engine light has

G'day mate , wow thats a lot wrong sounds like the vehicle has gone into LIMP mode where by you can only get it back to town for repair slowly, there's a real reason it has done this better take it to the man that fixes it properly

Posted on Apr 04, 2010

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2005 pontiac grand prix, code p0641 came on. What

DTC P0641 The powertrain control module (PCM) provides a 5-volt reference to the following sensors:

The throttle position (TP) sensor 1
The accelerator pedal position (APP) sensor 2
The engine cooling fan speed sensor
The AC pressure sensor
The fuel tank pressure (FTP) sensor
The oil pressure sensor (OPS)
The PCM monitors voltage on the 5-volt reference circuit. If the voltage is higher or lower than required, DTC P0641 will set.

Conditions for Setting the DTC
The PCM detects a voltage that is higher or lower than required on the 5-volt reference circuit. The above condition is present for 1 second. Action Taken When the DTC Sets The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
Conditions for Clearing the MIL/DTC The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. A current DTC, Last Test Failed, clears when the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. Clear the MIL and the DTC with a scan tool.

Yes i can be dangerous, depending which issues mentioned above has triggered the code such as a faulty gas peddle position sensor. the code can also cause a reduced engine power to activate.

Thank you for using Fixya and best advice is to have the dealer address these issues. A tech 2 scanner would be needed to address the P0641 DTC code.

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Reduced engine power

hi there my name is don i will try to help you on this
when your reduced engine light comes on that means there is a active fault code in one of the sensors that is cusing this
you will have to get it scanned or retreive the codes from the dash

once you shut it off and turn it back on it temporarly resets until the diagnostics go through it again and it will reduce the power to the engine
it could be something simple like a gas cap or tire pressure but you will have to get it scanned to find out

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