P203B code
Tuned
Joined: Nov 2016
Posts: 308
Likes: 14
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.
I'm not sure I understand what's being said. Why do you need to replace both batteries at the same time?
Update: The answer didn't matter for me. Both batteries failed load testing. Replaced and the CEL went off after 3 ignition cycles.
Trailering
Joined: Oct 2020
Posts: 23
Likes: 7
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."
"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."
New User
Joined: Dec 2021
Posts: 1
Likes: 0
P203b code on 2017 F-250
I have been having the p203b code show up over the last couple months. The dealer has replaced the wiring harness a couple sensors and the DEF heater. All was quiet for about a week after all this work. Now thinking it may be the batteries. I have also been having the clock automatically switch itself to 24hr time no matter how many times I switch it back.
Fleet Mechanic
Joined: Mar 2021
Posts: 1,454
Likes: 606
I have been having the p203b code show up over the last couple months. The dealer has replaced the wiring harness a couple sensors and the DEF heater. All was quiet for about a week after all this work. Now thinking it may be the batteries. I have also been having the clock automatically switch itself to 24hr time no matter how many times I switch it back.
Trailering
Joined: Oct 2020
Posts: 23
Likes: 7
I have been having the p203b code show up over the last couple months. The dealer has replaced the wiring harness a couple sensors and the DEF heater. All was quiet for about a week after all this work. Now thinking it may be the batteries. I have also been having the clock automatically switch itself to 24hr time no matter how many times I switch it back.
- DEF sensor fault
- Failed ignition start
- Remote start fails
- Clock reverting back to 24 HR
- Any other instrument panel issues with reverting settings to some default.
- Not replacing both batteries at the same time.
Cross-Country
Joined: Apr 2017
Posts: 81
Likes: 27
From: PGVa/AVON/PENSACOLA
Batteries can read 12/14 VDC and old theory tells you the battery is good..but todays vehicles require max cca's or "health" in this case.( 3 yrs min/5 yrs max) This has been going on since at least 05 to my knowledge, of instrument clusters/engine codes etc.. doing weird behavior due to low CCA's.
Cross-Country
Joined: Dec 2021
Posts: 95
Likes: 36
I have read that out-of-date DEF can cause the sensors to go bad. Be certain to always check the date on the DEF.
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1st Gear
Joined: Nov 2023
Posts: 1
Likes: 0
P203B
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.
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rtazz17
1999 - 2003 7.3L Power Stroke Diesel
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Dec 31, 2009 05:06 PM