How do you change sensors - 2009 Chevrolet Cobalt

if the codes read a EGR problem then that has to be fixed and not what the mechanic changed
Remember parts are available on line from anywhere in the world
sensors are different in construction so be aware that sensors before the cat converter are in fact HO2S ( heated sensors) while the one after the cat converter is a O2 sensor. They work in conjunction and signal the ECM program if the fuel mixture and cat converter is correct so that the fuel mixture cam be adjusted to keep the engine in tune.

presure sensor evap

P0340 FORD - Camshaft Position Sensor Circuit Bank 1 Sensor 1Possible causes- Faulty Camshaft Position Sensor
- Camshaft Position Sensor harness is open or shorted
- Camshaft Position Sensor circuit poor electrical connection
- Faulty starter motor
- Starting system circuit
- Dead (Weak) battery
P0340 FORD Description The Camshaft Position Sensor is an electronic device used in an engine to record the rate at which the camshaft is spinning. This information is used by the Engine Control Module(ECM) to control ignition and fuel injection. The camshaft position sensor senses the retraction of camshaft (intake) to identify a particular cylinder. The camshaft position sensor senses the piston position. The sensor system consists of a rotating part, typically a disc, as well as a static part, the actual sensor.

When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change. The changing gap causes the magnetic field near the sensor to change. The change in the magnetic field cause the voltage from the sensor to change.

When the crankshaft position sensor (POS) system becomes inoperative, the camshaft position sensor provides various controls of engine parts instead, utilizing timing of cylinder identification signals.
P0430, main catalyst is worn out.

p 0300 code is for random misfires
random misfires are more from dirty /faulty injectors or low fuel pressure than anything else
have a pressure test done to check pressure regulator , filter and pump operation
use a can of quality injector cleaner or remove and clean the injectors

you have to take it to the dealer to have it on a toyota computer and dial in all sensors.











TIM

p1391 is intermitant loss of signal from crank sensor and cam sensor--change sensors!! change cam sensor first. good luck!! then try it, if still same way. change crank sensor.

try getting a crank sensor from ford also use sandpaper and clean the mounting area of the crank sensor screws, and check all your fuses it is possible that one might have popped while you were prying off sensor none are marked that is why you have to check them all. if you end up changing you cam sensor it is recommended you change the synchronizer gear under the sensor you can purchase both as a kit for about 5o dollars.because if you don't you will soon hear a loud squeal from the gear causing you to go back to that area again.

You might try testing the tps. It may have a dead spot at the high end of the throttle opening. Make sure the resistance continues to change as you open the throttle all the way.

Throttle Position Sensor

Operation The throttle position sensor is a rotating type variable resistor that rotates with the throttle body-s throttle shaft to sense the throttle valve angle. As the throttle shaft rotates, the throttle angle of the sensor changes and the ECM/PCM detects the throttle valve opening based on the TPS output voltage.
Removal & Installation

1. Disconnect the negative battery cable.
2. Disconnect the sensor connector.
3. Remove the sensor retaining screws. Remove the sensor from its mounting.

To install:

1. Installation is the reverse of the removal procedure.

Testing 2.4L Engine

1. Disconnect the sensor connector.
2. Measure the resistance between terminal 1 (sensor ground) and terminal 2 (sensor power).
3. Specification should be 3.5-6.5 kohm.
4. Connect and analog ohmmeter between terminal 1 (sensor ground) and terminal 3 (sensor output).
5. Operate the throttle valve slowly from the idle position to the full open position, and check that the resistance changes smoothly in proportion with the throttle valve opening angle.
6. If the resistance is out of specification, or fails to change smoothly, replace the sensor.

2.7L Engine

1. Disconnect the sensor connector.
2. Measure the resistance between terminal 2 (sensor ground) and terminal 1 (sensor power).
3. Specification should be 3.5-6.5 kohm.
4. Connect and analog ohmmeter between terminal 2 (sensor ground) and terminal 3 (sensor output).
5. Operate the throttle valve slowly from the idle position to the full open position, and check that the resistance changes smoothly in proportion with the throttle valve opening angle.
6. If the resistance is out of specification, or fails to change smoothly, replace the sensor.

1. Disconnect the sensor connector.
2. Measure the resistance between terminal 2 (sensor ground) and terminal 1 (sensor power).
3. Specification should be 1.6-2.4 kohm.
4. Connect and analog ohmmeter between terminal 2 (sensor ground) and terminal 3 (sensor output).
5. Operate the throttle valve slowly from the idle position to the full open position, and check that the resistance changes smoothly in proportion with the throttle valve opening angle.
6. If the resistance is out of specification, or fails to change smoothly, replace the sensor.

3.5L Engine

1. Disconnect the sensor connector.
2. Measure the resistance between terminal 3 (sensor ground) and terminal 1 (sensor power).
3. Specification should be 3.5-6.5 kohm.
4. Connect and analog ohmmeter between terminal 3 (sensor ground) and terminal 2 (sensor output).
5. Operate the throttle valve slowly from the idle position to the full open position, and check that the resistance changes smoothly in proportion with the throttle valve opening angle.
6. If the resistance is out of specification, or fails to change smoothly, replace the sensor.

i would change mass sensor any way they cause lots of problems

Looks like an easy job.

Crankshaft Position Sensor: Description and Operation
CKP SENSOR (POS)
Component Description
The crankshaft position sensor (POS) is located on the cylinder block rear housing facing the gear teeth (cogs) of the signal plate at the end of the
crankshaft. It detects the fluctuation of the engine revolution.
The sensor consists of a permanent magnet and Hall IC. When the engine is running, the high and low parts of the teeth cause the gap with the sensor
change.
The changing gap causes the magnetic field near the sensor to change.
Due to the changing magnetic field, the voltage from the sensor changes.
The ECM receives the voltage signal and detects the fluctuation of the engine revolution.