Get it writing from the dealer & your butt is covered.

 

I experienced this EXACT same issue over the last couple of weeks. Check engine light came on and had some driver assist failures on the dash screen. I pulled the code myself and it was the P203B code yours has. I cleared the code and it came back within about 20 miles. Did this a couple more times. I then started noticing some issues with my remote start would not start the truck every time. It was becoming apparent that I was getting some battery lag. Popped the hood and found both batteries have appeared to have moisture on top of them. Took the truck to Advanced and had them tested. One battery was at 650 of 750 cold cranking amps and the other was at 300 of 750 cold cranking amps. Replaced the batteries, again cleared the code out for the P203B and ZERO issues since. About 1000 miles now. It appeared the low voltage started showing up first in the DEF system. Don't know why. I have read of many issues with batteries having to be replaced fairly quickly, yours may be one of them. Mine is a 2017 with 55,0000 miles.

 

Thanks for the info...same thing happening to me, but I've only got 8K miles on my 2017 (I work from home). I think my batteries hopefully are just low from lack of driving, but they could be on their way out as they are just ****** batteries.

 

 

 

 

Quote:
Originally Posted by RAAW Motorsports
I experienced this EXACT same issue over the last couple of weeks. Check engine light came on and had some driver assist failures on the dash screen. I pulled the code myself and it was the P203B code yours has. I cleared the code and it came back within about 20 miles. Did this a couple more times. I then started noticing some issues with my remote start would not start the truck every time. It was becoming apparent that I was getting some battery lag. Popped the hood and found both batteries have appeared to have moisture on top of them. Took the truck to Advanced and had them tested. One battery was at 650 of 750 cold cranking amps and the other was at 300 of 750 cold cranking amps. Replaced the batteries, again cleared the code out for the P203B and ZERO issues since. About 1000 miles now. It appeared the low voltage started showing up first in the DEF system. Don't know why. I have read of many issues with batteries having to be replaced fairly quickly, yours may be one of them. Mine is a 2017 with 55,0000 miles.

2017 Ford 250, I replaced drivers side battery 3 months ago. Just had engine light come up a week ago with P203b code, sure enough my passenger side battery was reading 452 cold crank amps and had it replaced. Pep boys cleared the code and no issues 200 miles in. Ford was asking to replace the entire diesel reductant tank for $1200. No need to! Thank you for the help.

 

This is an old post but still very much valid. I have a 2017 F250 6.7 Powerstroke. Check engine light came on around 55k miles. Code was P203B. I also noticed that the driver side battery, the positive terminal was severely corroded. Remote start would sometimes work and sometimes not work appearing to be weak signal problem. Cranking sounded slower than usual as well. I ended up taking the truck to the dealer and they quoted me $1500 to replace the DEF tank saying the sensor was bad. I raised holy hell with them because I felt like it should be under warranty since it is an emissions item. I declined their diagnoses thinking, for about the same price, I would rip the emissions stuff off the truck, get new exhaust and tuner. I went ahead and replaced the batteries myself after picking up the truck from the dealer. One of the batteries was completely dead and the other tested at 700 cranking amps. Once the new batteries were in, the check engine light went away on its own. The dealer mis diagnosed the problem. It wasn't the sensor failing, it was the battery not supplying enough power to the sensor causing the sensor to "fault".

 

Just for historical purposes of anyone else in the same boat, it was found my batteries were bad as well. Had them load tested at the local auto parts store. No CEL, so fingers crossed it's gone!

 

Never replace 1 battery of two on a diesel. Always both, same date code, charge them both before installing individually. I had the same replacement post battery failures in the summer. We. Not the same code, but tank, sensors and harness for DEF. I’m ok as it was still just under warranty. I did have to drive a fair ways, about 500 miles until I could get it looked at, never did get the limp mode. But eventually, anything to do with these types of codes will go into limp mode so you don’t want to be miles and miles away from a dealer that can help you.

 

It's your batteries. One has a dead cell or is not supplying proper voltage/amperage. I had this exact code and scenario under 70K miles. As luck would have it, this was something not covered by the 100K powertrain warranty.

Got my batteries load tested and replaced and never saw this or any other code again.

 

This is the Technical Service Bulletin put out by Ford regarding this issue / P203B error code:

https://ford.oemdtc.com/3260/illumin...d-f-super-duty.

I've had the same issue - there was some reason my batteries got low (maybe lights left on or maybe bad batteries - don't know yet). Got P203B code thrown. I cleared it with my OBDII reader and code came on again during my recent 400-mile trip with my 5th wheel. No limping kicked in just annoying to have to keep clearing the CEL.

Obviously, bad batteries should be replaced anyway. This TSB describes how to flash the Reductant Level Sensor, which has to be done using a special Rotunda tool only dealers have. Time for the job is stated as 0.4 hours and not covered under any extended warranty. One dealer insisted on doing their own diagnostics for $190. Another said they would flash the sensor without diagnostics but couldn't quote price.

Update 7/4/2021: Took my truck into Autozone and had them test both batteries. Their tester doesn't seem to be able to test CCA (cold cranking amps) but did say to replace the passenger side battery (even though it had 100% charge and good voltage. So just replace the one battery. The Autozone guy said the starter is on the passenger side, so might be pulling hardest on that battery? Anway, when I press the start button, the starter sounded so much more energetic and it started way quicker than in the past 9 months I've had this truck. No further issues with not starting, remote starting, or any engine codes. So bottom line, these trucks needs lots of juice to start, so an underperforming battery can really cause issues, even if it seems healthy with a simple voltage test.

 

I had the same issue with my truck 2017 F250. Service engine soon light came on and I couldn’t get an appointment at the dealership for a week. I’m set to pull my trailer in three days. Went to O’Reilly‘s and pulled the code which with P203B. Searched the Internet and found this thread regarding the batteries and sure enough one of my batteries was dead - the passenger side. Replaced the battery and the light went away on its own after 10 to 15 starts. I had replaced the driver side battery two or three months ago. Like one of the other users said on this thread I should have replaced both batteries at the same time. Thanks!!

 

Why do you say it's not covered. It says right here it is from the TSB.

"Warranty Status: Eligible under provisions of New Vehicle Limited Warranty (NVLW)/Emissions Warranty/Service Part Warranty (SPW)/Special Service Part (SSP)/Extended Service Plan (ESP) coverage. Limits/policies/prior approvals are not altered by a TSB."