I have been scouring online forums for tips on my van and haven’t found a lot of help, so I just made an account here and am hoping somebody can help me out. I live in my fully converted 2015 Transit 350 3.2L Powerstroke Diesel with my girlfriend on the west coast of the US, and have been since December 2021. It’s pretty important for our vehicle to be healthy.

About two weeks ago, we started noticing a strange blowing noise right behind the dash area and worse fuel economy (maybe 2 or 3 mpg). A few days later I took it to a diesel mechanic and he told me that there was an intake or exhaust leak somewhere in the system, but he didn’t have time to help me out. Next day, I had a different mechanic replace the fuel filter. Two days later, the check engine light came on, and we started seeing the “exhaust filter cleaning” pop up more often. Two days after that, we took it back to the first mechanic, who blamed the second mechanic for not priming the fuel filter properly and reset the check engine light. Next day, the check engine light came back on.

We are held to a tight schedule these next few weeks, and didn’t have time to bring it to the ford dealer (I have had bad experiences in the past with the service departments). So we drove 325 miles to my girlfriends family’s place (tight schedule), and I took it to the dealer here.

They ran their diagnostic test and came back with the P0170 Bank 1 code, and proceeded to do more tests. They eventually concluded that the NOx sensor is the problem, and no leaks in the intake or exhaust system are present. Verbatim from the report:

MX9-COMPARED O2 SENSOR READINGS, O2S11_PCT PID and the O2S12_PCT PID values are not within 2% of each other at idle MUST NSTALL a new Nitrogen Oxides Sensor Module 12 AND RECHECK

$423 later, and three days from needing to drive 680 miles, I am unsure what to do and whether or not it is safe or detrimental to our engine to drive that long distance. I’d like to get under the hood and see for myself if the intake system truly does not have any leaks, but I haven’t had a good opportunity to do so.

Has anybody else had experience with this? Does this sound like the dealerships is trying to jerk me off for a quick buck? Service advisor told me the NOx sensor was $480….

Thanks in advance for any help!

 

I would definitely be looking around under there for signs of exhaust or boost leak. That could also skew those sensors.

 

Turns out the upper intercooler hose was cracked. The mechanic I ended up going to said that it was an easy find and he was surprised the dealership missed it. I posted a bad yelp review for the dealership and they refunded me everything, even the NOx sensor I bought online.