P0641 engine power reduced

Hello,

This code has to do with the 5 volt reference the computer uses to run the system. This is typical of the computer going bad and needed replacement.

Please let us know what happens.

Cheers, Ken

You need to have the computer scanned to identify where the problem is coming from. Most parts stores will do it for free or lend you a scanner.

Hello,

This will be a camshaft angle sensor that is not working right. Here is a guide to help you see what you are in for when doing the job.

https://www.2carpros.com/articles/camshaft-angle-sensor-replacement

Here is where is is in your car

Check out the diagrams (Below)

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken

Yes I would change the sensors first because they have a high rate of failure if that doesn't work then we can start chasing wiring issues.

The 641 code is related to the other code as well. It has to do with a 5 volt reference voltage to the accelerator position sensor, which is the gas pedal.

You need to check the voltage at the sensor and see if you have this 5 volt signal at that sensor as well as the crank sensor as well.

Roy

Circuit/System Description

The engine control module (ECM) has 2 internal 5-volt reference busses called 5-volt reference 1 and 5-volt reference 2. Each reference bus provides 5-volt reference circuits for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference bus. The ECM monitors the voltage on the 5-volt reference busses.

The 5-volt reference 1 bus provides 5 volts to the following sensors:

* The manifold absolute pressure (MAP) sensor
* The fuel tank pressure (FTP) sensor
* The air conditioning (A/C) refrigerant pressure sensor
* The accelerator pedal position (APP) sensor 2
* The intake camshaft position (CMP) sensor

The 5-volt reference 2 bus provides 5 volts to the following sensors:

* The APP sensor 1
* The throttle position (TP) sensor 1 and 2
* The crankshaft position (CKP) sensor

Conditions for Running the DTC

* DTCs P0601, P0602, P0603, P0604, P0605, P0606, P0607, and P2610 are not set.
* The ignition is in Unlock, Accessory, Run, or Crank.
* The ignition voltage is more than 5.23 volts.
* DTCs P0641 and P0651 run continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM detects a voltage out of tolerance condition on the 5-volt reference 1 or 2 bus for more than 0.5 second.

Action Taken When the DTC Sets

DTCs P0641 and P0651 are Type A DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0641 and P0651 are Type A DTCs.

Diagnostic Aids

It may be possible to locate the fault by disconnecting one component at a time from the 5-volt reference circuit while viewing the 5-Volt Reference circuit parameter on the scan tool. The scan tool parameter would change from Fault to OK when the source of the fault is disconnected.

If all 5-volt reference components have been disconnected and a Fault is still indicated, the fault may exist in the wiring harness.

Circuit/System Verification

With the ignition ON and the engine OFF, observe the 5-volt Reference 1 and 2 parameters. The scan tool should display 4.3-4.7 volts for a normally operating system.

Circuit/System Testing

Important: Additional DTCs will set when disconnecting the components.

1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC.

Important: A short to voltage on the signal circuit of certain components may cause this DTC to set.

2. Ignition ON, measure for 4.8-5.2 volts between one of the 5-volt reference circuits and ground.

If the voltage is less than the specified value, test for a short to ground on all the 5-volt reference circuits. If all circuits test normal, replace the control module.
If the voltage is greater than the specified value, test for a short to voltage on all the 5-volt reference circuits, or the signal circuit, for each component associated with the appropriate 5-volt reference circuit. If all circuits test normal, replace the control module.

3. Connect each component associated with the 5-volt reference circuit, one at a time, while monitoring the voltage. The voltage should not change more than 1 volt.

If the voltage display changes more than the specified value when a component is connected, replace the component.

Repair Instructions

* Accelerator Pedal Position Sensor Replacement
* Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
* Control Module References for ECM replacement, setup, and programming
* Fuel Tank Pressure Sensor Replacement
* Manifold Absolute Pressure Sensor Replacement
* Throttle Body Assembly Replacement
* Camshaft Position Sensor Replacement - Intake
* Crankshaft Position Sensor Replacement

Repair Verification

With the ignition ON and the engine OFF, observe the 5-Volt Reference 1 and 2 parameters. The scan tool should display 4.3-4.7 volts for a normally operating system.

Did you check any of the tests on the flow chart?

Roy

Yes, it is related to both codes

Roy