Deleting trouble codes from ECU memory

laserbill · 06-01-2005, 12:49 AM

Having just joined the "ran out of gas and limped into gas station on battery power alone" club, I really would rather not share my stupidity (placing too much confidence in an optimistic mpg computer and funky fuel level gauge) with Toyota. It all worked out ok, and I was just glad I was piloting a Prius and not an airplane.
My question is can I delete any stored trouble codes from the main ECU by just disconecting the aux battery? I know that if I do, I will have to reprogram the radio, clock back up beep and possibly normalize the windows. Will this work and are there any tricks or things I should look out for?

**efusco** · 06-01-2005, 09:16 AM

They'll eventually self delete with enough restarts...I'm not sure how many. Also, if you go into the diagnostic screen I think you can delete the codes.

Really, this isn't something to worry about. Also, I'm not sure disconnecting the 12v would do the trick...I'm pretty sure the codes are stored in flash memory. There's not really any reason they'd need to check the codes.

laserbill · 06-01-2005, 09:50 AM

Thanks Evan,
I will search the site to learn more about the diagnostic screen and how to enter it. My thought is to read existing codes, and then monitor them if they are still there in flash prior to needing factory service. If so, I will consider deleting them through the screen or by disconnecting the aux. batt. I just don't want to be arguing with Toyota over some code if I ever have a hybrid/ battery problem in the future because I ran out of fuel.

DanMan32 · 06-01-2005, 10:40 AM

The diagnostic screen will let you delete the AVC trouble codes, but not the ODBII codes.

Removing 12v power may or may not cause the ECUs to lose their codes, though it is a good bet they will. Any CAN compatable scantool should be able to clear the codes, especially ECM codes.

laserbill · 06-01-2005, 08:42 PM

Thanks Dan Man,
It is a honor to get a reply from one of the most knowledgeable and active contributors at PC. Do you think having a flameout code residing in the ECU is worth worrying about? The SOC went down to one pink bar during my unwanted excursion in EV mode, power steeering was always working and the ICE started as though nothing happened once I put 11 gals in the tank. The car is acting completely normal after driving some 600 miles since.

DanMan32 · 06-02-2005, 03:31 PM

I probably wouldn't worry about it. Many have run it dry without ill effects. Some codes do erase after so many eventless trips, not sure if Out Of Gas and Engine Failed to Start are among those. Going down to 1 bar is definitely not a problem. HV would shut down the car before you got irreversably low in HV power, and would be able to re-engage READY at least 2 more times.

Frank Hudon · 06-03-2005, 04:44 PM

40 sucessful start cycles will erase all OBD11 codes from memory. Disconnecting the battery will not erase OBD11 but will on OBD1

laserbill · 06-03-2005, 05:27 PM

This site is amazing thanks to its members.

06-01-2005, 12:49 AM	#1
laserbill Join Date: Oct 2004 Location: Denver, Colorado Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Deleting trouble codes from ECU memory Having just joined the "ran out of gas and limped into gas station on battery power alone" club, I really would rather not share my stupidity (placing too much confidence in an optimistic mpg computer and funky fuel level gauge) with Toyota. It all worked out ok, and I was just glad I was piloting a Prius and not an airplane. My question is can I delete any stored trouble codes from the main ECU by just disconecting the aux battery? I know that if I do, I will have to reprogram the radio, clock back up beep and possibly normalize the windows. Will this work and are there any tricks or things I should look out for?

06-01-2005, 09:50 AM	#3
laserbill Join Date: Oct 2004 Location: Denver, Colorado Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Deleting trouble codes from ECU memory Thanks Evan, I will search the site to learn more about the diagnostic screen and how to enter it. My thought is to read existing codes, and then monitor them if they are still there in flash prior to needing factory service. If so, I will consider deleting them through the screen or by disconnecting the aux. batt. I just don't want to be arguing with Toyota over some code if I ever have a hybrid/ battery problem in the future because I ran out of fuel.

06-01-2005, 08:42 PM	#5
laserbill Join Date: Oct 2004 Location: Denver, Colorado Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Deleting trouble codes from ECU memory Thanks Dan Man, It is a honor to get a reply from one of the most knowledgeable and active contributors at PC. Do you think having a flameout code residing in the ECU is worth worrying about? The SOC went down to one pink bar during my unwanted excursion in EV mode, power steeering was always working and the ICE started as though nothing happened once I put 11 gals in the tank. The car is acting completely normal after driving some 600 miles since.

06-03-2005, 05:27 PM	#8
laserbill Join Date: Oct 2004 Location: Denver, Colorado Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Deleting trouble codes from ECU memory This site is amazing thanks to its members.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Deleting trace route on Navigation	flydeep	Audio and Electronics	7	11-26-2007 07:49 PM
Best diagnostic tool for reading trouble codes?	svallandigham	Prius Technical Discussion	7	11-26-2007 04:42 PM
Deleting Points in Nav Sys - HELP	OwenKealy	Care, Maintenance and Troubleshooting	4	05-20-2007 09:16 PM
Trouble Codes you never want to see	Tempus	Care, Maintenance and Troubleshooting	21	03-02-2006 06:50 PM
Deleting messages	IsrAmeriPrius	PriusChat Website Questions	4	11-07-2004 02:47 PM

06-01-2005, 09:16 AM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,253 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 24	They'll eventually self delete with enough restarts...I'm not sure how many. Also, if you go into the diagnostic screen I think you can delete the codes. Really, this isn't something to worry about. Also, I'm not sure disconnecting the 12v would do the trick...I'm pretty sure the codes are stored in flash memory. There's not really any reason they'd need to check the codes.

06-01-2005, 10:40 AM	#4
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	The diagnostic screen will let you delete the AVC trouble codes, but not the ODBII codes. Removing 12v power may or may not cause the ECUs to lose their codes, though it is a good bet they will. Any CAN compatable scantool should be able to clear the codes, especially ECM codes.

06-02-2005, 03:31 PM	#6
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I probably wouldn't worry about it. Many have run it dry without ill effects. Some codes do erase after so many eventless trips, not sure if Out Of Gas and Engine Failed to Start are among those. Going down to 1 bar is definitely not a problem. HV would shut down the car before you got irreversably low in HV power, and would be able to re-engage READY at least 2 more times.

06-03-2005, 04:44 PM	#7
Frank Hudon Senior Member Join Date: Jan 2004 Posts: 4,144 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	40 sucessful start cycles will erase all OBD11 codes from memory. Disconnecting the battery will not erase OBD11 but will on OBD1