Why would an ecm need to be reprogrammed?

[Chris142]

F450 where I work started throwing a p203b code. The repair is to reprogram the ecm.

But why would an ecm suddenly need to be reprogrammed after several years and 150000 miles?

If there was an issue why didn't it show up a long time ago?

 

[ctechbob]

Wild guess is that one of the counters in the ECU might be counting up and conflicting with some other program in the ECU, perhaps both trying to use the same memory location or there's just some kind of conflict in the programming that doesn't show up until later in life.

Could be any number of things that wouldn't show up till later on. Or maybe a weak sensor signal that might not be a problem, but the ECU was programmed with a more strict limit.

 

[GSCJR]

My guess is that as components age, they have a negative effect on their systems. In order to mitigate replacing parts that are technically still working, the parameters which they are designed to work in, are changed by the programming process to be now considered acceptable.

 

[brianl703]

If there was an issue why didn't it show up a long time ago?

Probably the original pass/fail criteria for the component programmed into the ECM was too strict.

The new program has pass/fail criteria that allows for greater variance.

GM has done the same with a few things on the Volt, for example the battery isolation resistance test and the acceptable signal from the crankshaft position sensor, both of which were loosened because the original program was failing these tests when there was actually no problem.

 

[jhellwig]

Wild guess is that one of the counters in the ECU might be counting up and conflicting with some other program in the ECU, perhaps both trying to use the same memory location or there's just some kind of conflict in the programming that doesn't show up until later in life.

Could be any number of things that wouldn't show up till later on. Or maybe a weak sensor signal that might not be a problem, but the ECU was programmed with a more strict limit.

If it was a plc from the 80s or the Apollo guidance computer I could see that. I would think a modern ECU could handle it but you never know when an engineer could have decided to save money.

 

[DemoFly]

They call it a reprogramming, because it's hooking up a computer to the ECM and technically rewriting the programming.

But it's actually recalibrating the level sensor.

 

[Chris142]

They call it a reprogramming, because it's hooking up a computer to the ECM and technically rewriting the programming.

But it's actually recalibrating the level sensor.

Wouldn't it make more sense to replace the level sensor?

 

[brianl703]

Wouldn't it make more sense to replace the level sensor?

Software is cheaper than hardware, in this case.

 

[DemoFly]

Wouldn't it make more sense to replace the level sensor?

Only if you want to keep buying level sensors.

 

[The Critic]

Ever do a software update on your phone?

Same idea.

 

[4wd]

Ever do a software update on your phone?

Same idea.

Mandatory on my Company stuff …

 

[Revving2Redline]

They call it a reprogramming, because it's hooking up a computer to the ECM and technically rewriting the programming.

But it's actually recalibrating the level sensor.

Sounds like they're changing the parameter values. There was discussion about this a while ago with some of the cars in the extreme winter.

 

[brianl703]

Maybe there's an unpatched critical vulnerability that would allow a remote unauthenticated attacker access to the system...

No, wait, that's Windows.

 

[supton]

https://repairpal.com/obd-ii-code-p203b-reductant-level-sensor-circuit-range-performance

implausible measurement. something off. not sure its reprogramming, maybe relearning, although at this age i would it needs a new sensor.