P0089 Code after fuel presure sensor change.
 

I have a 2007 S40, it was taking forever to crank. I thought is was a fuel pressure regulator, but I was told this model does not have one and it is the fuel pressure sensor. So I replaced the sensor. The fuel pressure went down from 61psi to 40psi and the car runs and accelerates a lot better. But after a few miles the CEL came on with a P0089 code. Also, I can now hear the fuel pump turning on and off, it is pretty loud, I don't remember it doing that before. Have any of you guys experienced this after a sensor change.

Thanks

Dan

I know this is an old post I'm responding to, but I have a very similar problem. My car (2006 S40 2.4i) was running horrifically bad, I was getting a P0304 (misfire #4) code all the time and every now and then P0300 (unknown or multiple/random misfire), and once or twice P0302 & P0303 (misfire #2 & #3). I was pretty sure I needed a new coil pack for #4, and I also decided to replace the spark plugs. Somewhere in there I decided that some of the symptoms went beyond a bad coil, and decided to replace the fuel pressure rail sensor too.

After doing that, the car runs great, but now I can hear the fuel pump really loud behind me, kind of a grating, whirring sound, and I'm now getting almost continuous P0172 ("System too Rich, Bank 1") code and frequent P0089 code as well. Also every now and then the car just dies when dropping to idle, but starts right up again and never seems starved for fuel when driving.

Seems like I have a failing fuel pump, but I don't get how that can connect to the P0172 code (if the fuel pump is failing, shouldn't the pressure be low, so how can it be running rich?), nor why I never heard it before the first time I started it after replacing the pressure sensor. Yeah, the car's been running rough for awhile, so maybe I just didn't notice it over the noisy/rough engine (but that seems tough to believe too).

At a loss for how to proceed other than the obvious course of replacing the fuel pump which is very expensive to have a shop do and probably beyond my capability to do myself. Plus I have no money, which makes speculative part replacement all the more difficult...

johnsonx42,
On my 2007 S40 the noisy pump was caused by me replacing the fuel pressure sensor with the wrong type. I think I used one for a turbo, and mine is not a turbo. I finally just re-installed the old sensor. My issue turned out to be a faulty one-way check valve on the pump. This can cause some crazy fuel pressure issues, and long crank times. If you have a fuel pressure gauge, connect it to the rail, watch the pressure while the engine is running. Then shut off the engine and watch the pressure, it should hold the pressure for several minutes; mine was instantly going to 0psi. Which means the one-way check valve was bad. The bad news, you cannot just purchase a check valve; you have to purchase the whole fuel pump assembly. rockauto.com has one for $280
I know is sucks to spend that kind of money, but I replaced the pump over three years ago and I have not had any problems from the car since. The gas mileage also returned to normal after installing the new pump. Also, you can do this yourself, just takes a little time. I have a small writeup here: ?07 S40 ? Fuel Pump Install | Turning a wrench
Dan

oh, man, I am so glad I posted in your old thread. your response was a wealth of valuable information...

I'll have to look very carefully at the part number of the sensor I bought, maybe I did get the wrong one. It was listed as being for my car and engine, but that info could have been wrong. I had been thinking about trying the old sensor again, but it seems to have made it's way out to the trash; I did the work at my dad's house, and my dad forgot that I wanted to hang on to the old sensor just in case. It's entirely possible nothing was actually wrong with it...

I don't think I have the check valve issue, as my car always starts up instantly (at least since replacing the fuel pressure sensor... before sometimes it would need a few seconds of cranking to start). Maybe I did indeed have a bad sensor, so replacing it with a working but incorrect sensor fixed a lot of the problems but caused these new ones?

I don't have a fuel pressure gauge, but I have watched the pressure graph on my OBDII app (Torque Pro)... it hovers around 40psi while idling, when I turn it off and then put the key back to ON without starting it, the pressure quickly drops to 20psi and then holds for as long as I care to watch (if I leave the key on ACC, the pressure also holds at 20psi, but it seems like I may not be getting live data because the graph is a perfectly straight line... with the key ON, there are slight undulations that seem more "real").

I'm also grateful for the write-up and photos of how to drop the tank and replace the pump. I've searched and searched and couldn't find anything about how to do it. Everything was for older S40's or other Volvos that had under-seat access, and I knew this car didn't have that. It may be that I actually don't need a new fuel pump, but it's good to know I can in fact do it myself if I have to.

I'll report back on what I find about the fuel pressure sensor I bought.

crap, Amazon screwed me. I went back to my order, clicked on the fuel pressure sensor I bought, and the part popped up with a red bar that says "!This does not fit your: 2006 Volvo S40 2.4 L5 Gas DOHC...". I KNOW it said it fit when I bought it! I used the filter by car function, and I made sure I had the green "This fits your car" message. If I switch the engine to the Turbo, then it says it fits!

this is the one I bought: https://www.amazon.com/gp/product/B005F9IZTO

(follow-up info: Standard Motor Products doesn't make a fuel pressure sensor for the non-turbo, and Amazon doesn't carry the correct Bosch sensor themselves... every seller I see says it'll take at least a week to get it. Now that I know I have the wrong sensor, I don't even want to drive the car... but I can't wait a week either... getting frantic)

so I got lucky... my dad called, said he found the old fuel pressure sensor. we were both looking for it in the box the new one came in, instead it was just wrapped in the plastic bag hiding on the workbench. I installed it, and sure enough, the fuel pump is silent again. The car runs fine with the old sensor, and the fuel pressure graph is as smooth as silk; with the wrong sensor it was very rough.

I'm thinking that the wrong sensor was calibrated for a different pressure range, so that the ECM interpreted the pressure as always being too low, and thus pounded on the fuel pump in vain trying to get the pressure high enough; meanwhile the actual pressure was way too high, and was pouring back against the pump through the check valve, causing the noise. If I'd driven the car much longer like that I probably would have destroyed the pump.

So this ordeal was largely self-inflicted: as far as I can tell I didn't need a new sensor in the first place, and I wasn't careful enough in cross-checking the part # I was buying. I should have just fixed one thing at a time. Lesson learned.

I told Amazon I wanted to return the part, selected "incorrect product information on the web site" as the reason for return. Looks like my return will be accepted, fingers crossed.

as an aside, the "Standard Motor Products" sensor I bought was indeed a Bosch part, it wasn't some generic or knock-off part. It was just the wrong one.

how lucky am I that dkchandler was still around and responded to my post on his thread from 3.5 years ago? who knows how far down the wrong path I might have gone. thanks dkchandler, and thanks volvo forums.

This may be a stupid question but is the Fuel Pressure Sensor and the Fuel Pressure Regulator the same thing essentially? After reading your thread I feel like maybe this could be my issue but when researching for a 2002 Volvo S40 1.9T all I'm finding is a regulator and not a sensor.

Like I said if it's a dumb question my bad

Hardly a dumb question... my understanding is that the 2005 and up S40 (mine) does not have a fuel pressure regulator; it uses the uses the fuel pressure sensor on the end of the fuel rail (which feeds the injectors) to measure the pressure and then precisely controls the fuel pump in the tank to keep the fuel pressure constant. There is no return line for excess fuel, as the pump is always delivering the exact pressure needed.

Conversely, I gather from what I've read that the previous model S40 (yours) uses a fuel pressure regulator to control the pressure in the fuel rail, while the pump runs constantly; this system does have a return line, and excess fuel flows back into the tank. There is no fuel pressure sensor, as the regulator sets the pressure.

That was a very good answer man, I almost certain the Fuel Pressure Regulator is going to be my next step. I've already bought a plethora of items and haven't fixed the issue yet. I have however made the symptoms a lot less, rough idle, occasional stall when coming to a stop, tough to crank afterwards, ect... I've replaced the coil packs, spark plugs, O2 Sensors, coolant temp sensor, and a few vacuum hoses and I've only made the symptoms slack and I've failed to completely fix it.

johnsonx42 ,
I am glad I was able to help. Sounds like she is running good again. I use Torque Pro also, great little tool. You are correct about the pressure sensor, it is just a sensor that talks to the computer to regulate the pressure. It's a good thing your Dad still had the part. That is why when I replace a part like that I keep the old one for a while just in case. Working on a Volvo is not like working on a Chevy, it is good we have forums like this to talk about these crazy issues.
Dan

so far so good after putting the old sensor back. No P0089 code, and while the P0172 code came back twice very soon after which was disconcerting, since clearing it yesterday morning it's not come back. Until now, even when I cleared it my code reader would show the P0172 almost immediately as a pending code, and the CEL would come on again within the next drive. I gathered it did have something to do with long term fuel trim, so it might have taken a couple short drives before the computer discovered the fuel trim coming back to normal.

curiosity question: I was surprised both times when I swapped the fuel pressure sensor, after draining all the pressure and fuel out of the fuel rail, when I started the car again it started immediately both times and ran perfectly. How did it not take at least a little extra cranking to fill the rail and bleed out all the air?

I guess the answer is what it has to be: at 55psi, the air compresses 4x and flies out through the injectors so fast there's no noticeable delay in fuel reaching the cylinders. Hopefully it's a sign of a healthy fuel pump that it brings the flow and pressure so fast.

I think when you turn the key to the on position it pressurizes the fuel rail. So by the time you actually crank the car it should have pressure. Yes, hopefully you will get several more years out of that pump.
Dan