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Q: my car started smoking out the back, smells like gas, shakes, and has loss of power. We checked using an obd2 sensor and found the

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Our car is an s60 volvo 2012. It has 100k miles. several months ago, back in December, the car started shaking, smoking really bad, losing power and the dealer said it was misfire in the second cylinder. Then we paid for that. They replaced the wires, and spark plugs. Then a month later the same thing but now it was a misfire in cylinder 4. We paid for that repair. All very expensive. Now a month later, the same thing. The code is 2238 and 302 meaning misfire again in number 2 cylinder and faulty o2 sensor. Now is the sensor causing the misfire or is the misfire causing the sensor code? Now the car won't start.

My car has 109000 miles.
My car has an automatic transmission.

Hi there. You have a valid question; is the O2 sensor causing the misfire or the misfire setting the O2 sensor code. This can simply be answered by viewing data and performing proper tests on the systems in question by the stored codes. Before agreeing to replacing any parts always ask why and to be shown the failed part with a proper explanation. If the O2 sensor is faulty then the technician should be able to explain why/how and show you. If there is a different part that is faulty then the same applies, ask why/how and to be shown. Data on a capable scan tool can be shown and compared against manufacturer specifications. Simply put, here is the min/max and here is where your sensor is operating. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection.

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