Possible Fuel Pressure Sensor/Regulator & MAF Issue

Neveragain55 · Post by **Neveragain55** » 30 Jan 2026, 13:02

Hi Gang….

So, last night I’m driving home from Massachusetts back to Connecticut and just before Hartford, my 2009 S60 2.5T AWD starts bucking like a wild bronco horse.

I swear to God I thought the car was going to come apart and I had absolutely no idea what the hell was going on.

Once the car started bucking & surging really badly, I pulled into a gas station, turned the car off to check everything and she looked fine.

I started her back up and she idled perfectly and ran great for another 10 miles or so and then the bucking & surging and poor acceleration came back and it stayed.

I limped her home that way, but there’s no way I’m taking her back out until I figure this out.

I have sank a ton of money into this car everywhere recently, including brand new tires, new coil packs, wires, plugs, filters, engine mounts, CV axles, new shocks, new front end bushings, and a lot more.

Most of that work was done a few months ago so I know that all of the electrical work was solid and I can rule those issues out.

I don’t dog the car out and I don’t race the engine, and she always humming along like a sewing machine…..until last night.

All research leads to either a bad fuel pressure sensor/regulator, MAF, or both.

I used my iCarsoft Volvo scanner today and got no codes at all for either one of those components. The only codes I got was for the traction control system but that lights been on since I bought the car and I completely ignore it.

I think the reason why I got no codes for the fuel sensor/regulator & MAF is because from what I’ve seen online, those components intermittently act up before they completely go, and the car is running smooth today.

I’m tempted to just buy those pieces anyway because since I’ve owned the car, they’ve never been replaced and I have no idea if the components that are on the car now are original. (in all likelihood, they are)

Any and all opinions or tips from experience with this would be greatly appreciated, thanks in advance gang…

Neveragain55 · Post by **Neveragain55** » 31 Jan 2026, 15:08

Don't everybody jump in at once......

I replaced the fuel pressure sensor and the MAF today and so far, so good.

I'll report back in later after a few hundred miles with an update.

Hopefully this post and this fix could help somebody out in the future if they have a similar issue.

Post by **abscate** » 02 Feb 2026, 03:55

Is a 2009 a p2 chassis ( this forum) or a P3 chassis? You might be trying to get Communion while sitting Seder….

Sorry we passed you over…

My p2 PEM failed years ago with no codes, a bit of missing under load amd then a no start.

The fuel pressure sensor went and that was a cut out of power, but it also coded

Post by **jonesg** » 02 Feb 2026, 05:29

all those parts, or the pump or filter or PEM.
a cheap $12 ELM 327 for your phone with the free torque app will show fuel pressure whilst running.

Post by **br0dy519** » 02 Feb 2026, 09:48

It kind of sounds like a misfire. I wonder if you have a vacuum leak, or if the throttle body is giving out. Needs a DICE setup to diagnose correctly. Clean the TB and inspect hoses just to be certain.

Post by **cn90** » 02 Feb 2026, 17:28

Probably bad PEM as mentioned.

I have a few good PEMs lying around, lmk if you want it.

Post by **chrism** » 02 Feb 2026, 17:30

jonesg wrote: ↑02 Feb 2026, 05:29 all those parts, or the pump or filter or PEM.
a cheap $12 ELM 327 for your phone with the free torque app will show fuel pressure whilst running.

I’m curious, if the fuel pressure sensor is sending false information then will the app present that same (false) info?

Post by **erikv11** » 02 Feb 2026, 19:28

Like everyone else I am replying only with p2 knowledge and the OP's car is not a p2 but ...

1 my first guess is fuel supply, agreed!

2 also sounds similar to the symptoms my 06 S60 showed when the throttle body needed cleaning, at 186k miles. the stumble was dramatic and then it died; would start back up and run fine for a while. It also gave a throttle body code in VIDA.

Post by **br0dy519** » 02 Feb 2026, 21:21

chrism wrote: ↑02 Feb 2026, 17:30
jonesg wrote: ↑02 Feb 2026, 05:29 all those parts, or the pump or filter or PEM.
a cheap $12 ELM 327 for your phone with the free torque app will show fuel pressure whilst running.
I’m curious, if the fuel pressure sensor is sending false information then will the app present that same (false) info?

(full disclosure neither of my cars have a FPS nor PEM)

Yes. Fuel PSI reading on the scanner would be a direct output of the sensor. Easy to check if you have a gauge connected. Look at your digital readout, vs the physical gauge. Difference should be negligible, if any. If it's anything like the pressure sensors I'm used to seeing in HVAC, it's a tranducer on a 3-wire output.

Post by **cn90** » 02 Feb 2026, 21:44

erikv11 wrote: ↑02 Feb 2026, 19:28 Like everyone else I am replying only with p2 knowledge and the OP's car is not a p2 but ...

The 2009 S60 is a P2 car.