How to Diagnose P0521 Failed Sender Code

Hi. I'm Mike from 1AAuto. We've been selling auto parts for over 30 years!

Alright so we have a oil pressure issue with our 2009 Chevy Suburban. We actually have a code for the oil pressure sensor range performance. We notice when we start the vehicle, if you look over at the oil pressure gauge, when we start it, it is stuck at 0. Now we know we have oil pressure because we can hear that the lifters are not clanking. We know that the top of the engine is getting oil, but the gauge is down to 0 and like we said, we had the code for it.

At one point, this gauge was reading 80 up, as you can see. It's up to 80 right now, okay. As you can see, the gauge is jumping all around while the engine's running. This is the switch sending a faulty signal to the gauge.

So, I'm going to shut the car off right now. I'm just going to turn the key on. Let's see what the needle does. Okay so right now, it's stuck on 80 with the engine off. Now we know obviously there's not that much oil pressure at the sender, while the engine's off. So what we can do now – oh it just dropped down to 0, but what we could have done is when it's stuck at 80, we could disconnect the sensor, and if it drops to 0, then you know it's definitely the sensor.

Remove this cover. Just lift up and then just wiggle it forward. It comes off. Okay the oil pressure's sensor is on the back here; it's really hard to get to. You can struggle to try to get that connector off. What you'd have to do is pull the lock tab up a little bit and then squeeze the lock on the connector and then pull the connector off. If your oil pressure was stuck at 80, and when you did that, it dropped to 0, then that's 100%, that would be the oil pressure sensor, or oil sender that needs to be replaced because it's shorted internally. There's the sensor.

Some vehicles have an oil screen down here, what you can do is take in a pick and just slide it down in here and pull up. Pull up and there's the screen. Generally these will clog up with debris. Sometimes it will give you a false reading. Basically, you'll have no oil pressure at the sensor. You put a new sensor in it and it's still not reading pressure, and because this screen is dirty. So you can either clean it out with some brake parts cleaner or replace the screen like we're going to.

Alright, at this point we already replaced the oil sensor, so we're going to check it now. We'll just turn the key on. Then as you can see, the oil pressure gauge is sitting there at 0 which is good. So now I will start the vehicle, and as you can see, that the oil pressure gauge is actually reading accurate, what the actual oil pressure is. So we repaired the vehicle.

Thanks for watching. Visit us at 1AAuto.com for quality auto parts, fast and free shipping, and the best customer service in the industry.