In the past few weeks my car (2005 s60 Turbo) began experiencing what I thought to be shift flares. With my foot on the gas, the car would suddenly lull (felt like it was pulling back) and then slam forward creating an overall jerking movement. I would be at a constant speed and this would suddenly happen. Occurrences of this have been random, but happen on the highway. Only once has the car felt like it wouldn't accelerate and then I see the needle flare and driving returned to normal. The main problem has been the random and sudden lull and engage, which happens mostly around 2nd gear. The car has approximately 126K miles.

I took the car to my local shop and said I thought I was experiencing shift flares and described the problem, which they couldn't replicate during their test drive. I had them update the TCM software and do a transmission fluid flush (transmission fluid was dirty). I asked if replacing the B4 Servo Cover would alleviate the problem (because I saw that solution on Volvo Forums) but they said that didn't apply to my car. They told me I would need to replace the valve body cover but it wasn't a guaranteed fix.

After the TCM update and the flush I am still experiencing the issue, although they seem to have become more subdued. What has happened since is, right after the car lulled and engaged, the Check Engine Light came on. I took the car back to the same shop and they scanned it and it showed that ECM codes had been triggered but were now fine. These are the codes that were triggered and the status reported when I had the shop scan:

ECM-440B Fuel Level sensor - Signal missing (Status: DTC is found not active)
ECM-280B Fuel pressure sensor - Signal missing (Status: DTC is found not active)
ECM-280C Fuel pressure sensor - Signal too high (Status: DTC is found not active)

The check engine light went off after I left the shop, but the same thing happened again a couple days later--car lulled and engaged, check engine light came on right after, then went off after a couple drive cycles.

What I'm wondering now is if the problem is actually with my fuel pressure sensor and that is resulting in the car jerking.

Any help would be GREATLY appreciated!!

Thanks

 

See if your local dealer will fix the pressure sensor for free. I brought mine to the dealer a year ago to have a new key made. They plugged my car into their computer system then mentioned the fuel pressure sensor issue and said that the sensor was a recall item and they would fix it for free right then and there, and thats exactly what they did. No charge or any further comments just fixed it, gave me the key and I was out the door.

I already had a check engine light for an emission problem so I don't know if they saw the code you got or not.

 

Turns out that the issue was the fuel pressure sensor. I had it replaced and have been driving the car everyday for a over a week and the issue has gone away. Unfortunately the repair was not covered under a recall like it has been for other years.