2006, 2.2L, with 239,000 miles...Driving on the highway the other day and the SES light comes on. Pull off and check the code with scanner and it's a P0326 Knock Sensor. The engine did have a slight "tick" to it. After two days of start up the ticking seemed louder and the light was still on.

I was at 10% left for an oil change (about 6,000 mile mark using full synth Mobil 1 5w/30) so I decided to change the oil this weekend and pull the knock sensor. After the oil change I ran out of time to change the sensor so I did NOT, and for the last 2 days the light is not on and the engine knock is barely noticeable. Could it be that the sensor had some build up on it and the new oil helped to clean it off?

I was at full mark on the dipstick prior to the change too. Anyway, I am holding off on the KS replace unless the light comes back on.

Thoughts?

 

The knock sensor does not go into a oil passage. My guess would be the motor is not as noisy now so you are not tripping a knock sensor code.

The big question is why is the motor less noisy now after the oil change. Did you put heaver oil in it?

 

Read this: http://www.obd-codes.com/p0326

 

Same 5w/30 as always. Wasn't sure if the sensor came in contact with oil so thanks for clarification on that. Is it possible it was just a bad batch of gas. Always use 87 octane, but maybe the winter/spring blend was off at last fill up?

 

Great write up. Thanks.

 

If my memory serves, the KS is right there next to the oil filter cap, easy to jiggle. And older cars get jiggled more over time.

 

He MAY have lost the oil's viscosity. Although I have not heard of "regular" Mobil 1 experiencing that problem. Mobil 1 Extended Performance has been known to migrate to a 5w-20 SUS. I have experienced it on 5 oil changes on 3 different vehicles. Going back to regular Mobil 1 next change.

That could explain a lifter noise. Doubt it would affect the Knock Sensor.

 

With over 235,000 miles on this car I have been using Mobil 1 High Mileage for the last few oil changes.

 

"HIGH MILEAGE OIL" is not good for engines with high mileage.

They usually contains extra Zinc and other heavy metals that will poison the cat and foul the O2 Sensors if you are burning oil.

 

Really? I have 5 GM vehicles 3 Trucks, 1 blazer and the HHr and 3 with 250,000 + miles on them and used Mobil 1 HIgh Mileage version in a couple of them with no problems. I have a 91 pickup with 568,000 miles (yes original engine) that I started using Synthetic oil on at 50,000 miles and have used the High Mileage version in that engine as well. No Zinc levels or issues with 02 sensors in that truck. I have an oil analysis done by an independent lab every 3rd oil change (always change at 5K) and the highest the zinc levels have been are in the 800-810 range where universal averages are in the 810-850 range.

Not doubting what you are saying, just giving my experience. If you have a report or white paper to back this up I'd love to read it.

Thanks,