Code P0521

Jrue03 · February 18, 2020

I have a 2010 Chevy Silverado 5.6 with 78k and have had the engine light come on multiple times and it reads the p0521 code. I had the engine oil pressure sensor changed. The light didn’t go off and I changed my oil and the light went off. It has now come on again about 4K miles later and the oil pressure is at about 38 when driving and around 20 when at a stop light. I changed the oil and filter with Pennzoil full synthetic oil and a Mobil 1 oil filter. I have driven the truck about 50 miles since and the light still remains on. Anyone else have a problem like this?

swathdiver · February 19, 2020

On 2/18/2020 at 7:53 AM, Jrue03 said:

I have a 2010 Chevy Silverado 5.6 with 78k and have had the engine light come on multiple times and it reads the p0521 code. I had the engine oil pressure sensor changed. The light didn’t go off and I changed my oil and the light went off. It has now come on again about 4K miles later and the oil pressure is at about 38 when driving and around 20 when at a stop light. I changed the oil and filter with Pennzoil full synthetic oil and a Mobil 1 oil filter. I have driven the truck about 50 miles since and the light still remains on. Anyone else have a problem like this?

Was the screen underneath the sensor replaced or cleaned? Did you use GM OE or ACDelco Professional parts?

My own experience with M1 EP oil filters is that they are more restrictive than stock and lowered my oil pressure about 3-5 psi. I now run the K&N which flows twice as much oil, filters down to even smaller microns and my oil pressure is "normal" again, the same as the ACDelco filter. Is your motor the all aluminum LC9? They run less oil pressure and pump 1/3 more volume per revolution than the LMG iron block motor.

The code is telling you that the pressure difference between the sensor and predicted is less than 6.8 psi or more than 7.3 psi. A bi-directional scan tool like the Tech-2 can view failure records.

Three options, bad sensor, wiring or ECM.

Jrue03 · February 20, 2020

Thank you for the help. I have the LC9 engine. The engine light has gone off after about 50 miles on the new oil and oil filter. Do you have a suggestion on oil filter? Should I try the K&N next time I change everything?

swathdiver · February 23, 2020

On 2/20/2020 at 1:45 PM, Jrue03 said:

Thank you for the help. I have the LC9 engine. The engine light has gone off after about 50 miles on the new oil and oil filter. Do you have a suggestion on oil filter? Should I try the K&N next time I change everything?

I really like the K&N, the nut on the bottom makes it easy to snug up and take off. I also run the longer filter, HP-2011 instead of the HP-1017. The K&N flows 960 GPH versus 672 for M1 and filters down to 10-12 microns versus 30 at the same 98% rating. They're readily available at Walmart or Amazon.

I also dumped M1 oil for ACDelco's but that is another story. My truck is also powered with an LC9, a wonderful motor.