02 a4 1.8t a lot of codes coming up idk where to start
01-14-2016, 11:45 AM
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03-06-2016, 05:09 PM
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Let's tackle this as 2 sets of problems.
Set 1
P0300, P0301, P0302, P0303
These are all misfire codes. Work through it in steps. First thing is go get a fresh set of plugs. Go with a good Bosch or NGK plug. Also, pay attention for a flashing check engine light. This indicates a misfire. See if you notice a pattern. Does it happen on cold days, rainy days, days where you havnt driven the car for a while? If that doesn't correct it, change your coils. The 1.8t coils are notorious for failure. Worst case scenario would be to check the coolant for exhaust. A leaky head gasket can cause a cylinder misfire at startup until the coolant has been pushed out of the cylinder.
P0011 - This coming from a sensor located in the front of the engine under the timing cover. To check this there are two clips, one on either side of the cover. Pull the two hoses on the front of the cover free and it will lift out. The sensor is to the right of the cam sprocket. It has 2 10 mm bolts on it and there's a spring on the wiring harness you push to release it. It had burnt and the magnet had come off on my Passat.
Set 2
P0411, P0420
These are to do with the catalyst and emissions and aren't a big deal if you live in an area that doesn't have smog tests. I have removed the catalyst and written these two codes out of my A4. You likely need a new catalytic converter to get one of the codes to go away. The other one has to do with a pump that runs at startup. Listen to hear it. It's on the passenger side of the engine bay. It only runs for the first 10 minutes on cold days to get the system up to temperature. You likely have a leak in the hose that connects the pump to the combi valve on the back of the head.
Set 1
P0300, P0301, P0302, P0303
These are all misfire codes. Work through it in steps. First thing is go get a fresh set of plugs. Go with a good Bosch or NGK plug. Also, pay attention for a flashing check engine light. This indicates a misfire. See if you notice a pattern. Does it happen on cold days, rainy days, days where you havnt driven the car for a while? If that doesn't correct it, change your coils. The 1.8t coils are notorious for failure. Worst case scenario would be to check the coolant for exhaust. A leaky head gasket can cause a cylinder misfire at startup until the coolant has been pushed out of the cylinder.
P0011 - This coming from a sensor located in the front of the engine under the timing cover. To check this there are two clips, one on either side of the cover. Pull the two hoses on the front of the cover free and it will lift out. The sensor is to the right of the cam sprocket. It has 2 10 mm bolts on it and there's a spring on the wiring harness you push to release it. It had burnt and the magnet had come off on my Passat.
Set 2
P0411, P0420
These are to do with the catalyst and emissions and aren't a big deal if you live in an area that doesn't have smog tests. I have removed the catalyst and written these two codes out of my A4. You likely need a new catalytic converter to get one of the codes to go away. The other one has to do with a pump that runs at startup. Listen to hear it. It's on the passenger side of the engine bay. It only runs for the first 10 minutes on cold days to get the system up to temperature. You likely have a leak in the hose that connects the pump to the combi valve on the back of the head.
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