Outback wagon no power going up hills.

The knock sensor code does not always mean the sensor is faulty.
The sensor picks up noise and vibration in the engine such as a spark knock would generate, and the computer slows down the spark timing to fix it. If the noise or vibration continues, the code is set.
Could be a noisy valve, or a problem with the crankshaft or other component.

You have to hook an OBD 2 scan tool up to the data link connector and check to see what code is present. If you have a knock sensor code, you need to replace the knock sensor. If you get a P0420: Catalyst system efficiency below threshold, you will need to replace your catalytic converter. But if it is nothing important, the only way to clear a check engine light is with a scan tool. You can usually go to any aftermarket parts store and they will check and clear you codes and light for free. I hope this info helps.

free check engine code read at auto zone. we replaced a sensor 15$ our spark knock sensor is still out but ran fine for two years. a month ago lost power sputtered with ac on , turned out to be a spark plug wire 29$ set of four we replaced ours with one we had from another car runs great again

I would change it anyway. I would scan it again and see if the knock sensor code is stored.

I have this same vehicle. The "check engine" light warns you that the input from a sensor is not valid. To locate the problem sensor you need to have the fault codes downloaded and interpreted. I am sure your PCV has little to do with this. The burning smell cold be oil from your transaxle seals being thrown up onto the exhaust pipes. The outback is a sophistecated and refined vehicle that requires sophisticated equipment to work on it. If you have engine "knocking" it is likely to be the knock sensor and if this is the case, you need to have it remedied very quickly

I do not know for sure if this is the problem you are having, But, I have noticed that from 95 up to 2002 I have seen a lot of PO420 codes that have been just the sensor. I do not know if it was a weak sensor or just that program telling it that it is below threshold. I did notice that if the vehicles are run for a long trip at highway speed it goes out. I wish you luck and have a great day.

A p0420 code is set when the computer determines that the catalytic converter isn't doing it's job. In almost all instances that code can't set as a result of a bad o2 sensor so they probably didn't have to be replaced. The catalytic converter will need to be replaced, prefferably by an oem part. This can be pretty expensive and should be considered before purchasing the vehicle.

I have replaced a few bad converters on late model subarus in the past few years.

Check your tail pipe for color. If insides are black you are running rich and it all may boil down to an oxygen sensor or an EGR valve. EGR valves are the most common causes for the 'check engine' light to come on. Your trouble codes will tell you what it is. Some auto stores will check it for free or you can buy an inexpensive checker.

Get the P code read at your local parts chain store for free. It sounds like you need to find this out very soon. The code will tell you exactly what part is failing.

PO420 is for catalyst system efficiency below threshold. I have seen this many times on vehicles from 96 up. It is due to the system not burning the fuel at what it considers an acceptable rate. Todays fuels are not the best we could have for internal combustion and sometimes it will set off the light. I tell my wife she is too easy on the car and it's not burning the fuel proper. After a couple days it goes out. It will not harm your engine and should go out again. Fuel system cleaning additive will also turn of light. Good luck and enjoy your Subbie. Greatest car ever Built.