Check engine light/Volvo S60, 2004
 

2 weeks ago we started getting the 'check engine' light on. Orange, solid. I called Volvo and they said that majority of time it is the gas cap. I tightened it..and 2 days later it went off. Now, 1 week later, it is on again. Went down to our lcoal mechanic who pulled the code and said "front catalytic converter" code. He also said that he reset the light and deleted the code. 2 months ago we had our rear catalytic converter done (diagnosed with a Volvo specialty mechanic shop). We don't hear any noise coming from the car as when we did when the rear started giving us problems. The rear one did not give any check engine indicator light at all before fixing it. The fact that the light turned off after 2 days, then came back leads me to believe it may be a sensor problem. I am wondering what the best approach would be. Based upon the above information provided, what could it be? Is there anyway to trouble shoot this with a exclusion method without breaking the wallet?

Many things could cause this code to come on. A dirty mass air flow sensor or bad oxygen sensors can cause this code.

check engine code
 

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