I have a Chevy 2006 Aveo. Two codes came up when the engine check light was put on a scanner. Code P0340 and Code P0133. The check engine light has turned off and on by itself several times in the last week. What is the problem?

P0340 OBD-II Trouble Code - Camshaft Position Sensor Circuit Malfunction

This indicates that a problem was detected in the camshaft position sensor circuit. Since it says circuit, that means the problem could lie in any part of the circuit - the sensor itself, the wiring, or the PCM. Don't just replace the CPS (camshaft position sensor) and think that will definitely fix it.

Symptoms can include:
* Hard starting or no start
* Rough running / misfiring
* Loss of engine power

Causes: A code P0340 could mean one or more of the following has happened:
* a wire or connector in the circuit could be grounded/shorted/broken
* the camshaft position sensor may have failed
* the PCM may have failed
* there exists an open circuit
* the crankshaft position sensor may have failed

Possible Solutions: With a P0340 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
* Visually inspect all the wiring and connectors in the circuit
* Check for continuity in the circuit wiring
* Check the operation (voltage) of the camshaft position sensor
* Replace the camshaft position sensor as required
* Check the crankshaft position circuit as well
* Replace circuit wiring and/or connectors as required
* Diagnose/replace the PCM as required



P0133 OBD-II Trouble Code - Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)

This involves the front oxygen sensor on Bank 1. This code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use.

Symptoms: You will likely not notice any drivability problems, although there may be symptoms.

Causes: A code P0133 may mean that one or more of the following has happened:
* The oxygen sensor is faulty
* The wiring to the sensor is broken / frayed
* There is an exhaust leak

Possible Solutions: The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is more than likely the front Bank 1 oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions:
* Check and fix any exhaust leaks
* Check for wiring problems (shorted, frayed wires)
* Check the frequency and amplitude of the oxygen sensor (advanced)
* Check for a deteriorating / contaminated oxygen sensor, replace if necessary
* Check for inlet air leaks
* Check the MAF sensor for proper operation


Hope this helps (remember to rate this answer).

Ok P0133 is your 02 sensor failing on bank one and P0340 is your camshafth position sensor also at fail, this is intermintent at this time but will get to a point were it will stay ON all time, replace 02 sensor they lost precison over time ,mileage, contamination etc. you did not specify eng miliage, some manufacturers recomend replacement arround 60,000 miles,
On the other hand your cam sensor may have contamination in it, remove clean it, and if code comes back replace give your self a chance, vehicle wont stall on you because computer still have a crank sensor signal to go with it, but dont wait to long,
good luck

P0340 = camshaft position sensor "A" circuit malfunction (bank 1)

P0133 = O2 sensor circuit, slow response (bank 1, sensor 1)

bank 1 indicates the side of the engine that includes cylinder 1
bank 1, sensor 1 indicates the side of the engine that includes cylinder 1 before the catalytic converter.

The camshaft position sensor maybe starting to fail or the wiring to it has loose connections.
The O2 sensor is getting old and not switching back and forth quickly enough for it to an accurate sensor anymore.