Check Engine Light - Reset question

[ToyoTundra]

Hello,

I already did a search, but it provided various opinions.

My question is this:

If a CEL comes on, then you fix the issue, can you clear the ECM (or whatever it's called) by simply disconnecting the battery??? I know it resets the light on the dash, but does it also clear out the error code from the ECM???? Or, will the ECM have to to be cleared using a OBDII(?) tool???

Thanks!

[nhparrot]

Hello,

I already did a search, but it provided various opinions.

My question is this:

If a CEL comes on, then you fix the issue, can you clear the ECM (or whatever it's called) by simply disconnecting the battery??? I know it resets the light on the dash, but does it also clear out the error code from the ECM???? Or, will the ECM have to to be cleared using a OBDII(?) tool???

Thanks!

Yes disconnecting the battery will work or it will shut iteself off after 3 trips with no codes being registered.

[ToyoTundra]

Yes disconnecting the battery will work or it will shut iteself off after 3 trips with no codes being registered.

If you could explain...... wouldn't it already have registered a code, so even after 3 trips and the CEL goes off the code is still in the memory???

To confirm: disconnecting the battery WILL reset BOTH the CEL as well as clearing ALL codes in the memory???

[jross]

I also need an answer to this question.
My O2 sensor went out and I replaced it myself...saving $200 from what the dealer wanted to replace it.
However, the CEL is still on. I disconnected the battery, and it worked....momentarily. The next time I started my truck, it came bcak on.
Dealership wants $80 to reset!!!

[nhparrot]

If you could explain...... wouldn't it already have registered a code, so even after 3 trips and the CEL goes off the code is still in the memory???

To confirm: disconnecting the battery WILL reset BOTH the CEL as well as clearing ALL codes in the memory???

When a malfunction is first detected, the malfunction is temporarily
stored in the ECM memory. This is known as 1st trip detection.
If the ignition switch is turned OFF and then ON again, and
the same malfunction is detected again, the MIL will illuminate.
This is known as 2nd trip detection.

If the malfunction does not reoccur in 3 consecutive trips, the
MIL goes off automatically but the DTCs remain recorded in the
ECM memo

[ToyoTundra]

When a malfunction is first detected, the malfunction is temporarily
stored in the ECM memory. This is known as 1st trip detection.
If the ignition switch is turned OFF and then ON again, and
the same malfunction is detected again, the MIL will illuminate.
This is known as 2nd trip detection.

If the malfunction does not reoccur in 3 consecutive trips, the
MIL goes off automatically but the DTCs remain recorded in the
ECM memo

Ok, so assume all that....... HOW do you clear the DTC's from the ECM memory???? Can this be done by disconnecting the battery or do you need an OBDII tool to reset it, ??????? This is the piece I am missing. Thanks!!

[Big Black Tundra]

i went to the dealer and he told me to turn off engine then put it on the on position but dont start and then hold the trip botton on the odomiter. when it flash twice release then it is reset this works with only 05 model and up i think

[sootie]

Ross there are 4- 02s on the Tundra .....I think they register as left bank- right bank regarding the error codes...so you have a 50-50 chance of replacing the right one. I could be wrong .....but something to consider. Good luck.

[ToyoTundra]

Ok, so assume all that....... HOW do you clear the DTC's from the ECM memory???? Can this be done by disconnecting the battery or do you need an OBDII tool to reset it, ??????? This is the piece I am missing. Thanks!!

Does anyone know for sure what CLEARS the ECM?????

[nhparrot]

Per the service manual it can be done using the Toyota Handheld Tester or by without the tester by:

Remove the EFI No. 1 and ETCS fuses from the engine room J/B for more than 60 seconds, or disconnect the battery terminal for more than 60 seconds.

[jross]

Sootie, The printout from the inspection place told me which sensor was out.

I will try the whole fuse thing...disconnecting battery didn't work (worked temporarily).

Thanks guys

[nhparrot]

Sootie, The printout from the inspection place told me which sensor was out.

I will try the whole fuse thing...disconnecting battery didn't work (worked temporarily).

Thanks guys

If disconnecting the battery did not work, there is something still triggering the MIL, have it read with an OBDII reader to see the code and that will point to the problem.

[ronhohu]

Try Autozone. Use their ODB II scan tool. The scan tool will let you clear all the codes. And it's FREE.!!!

Does anyone know for sure what CLEARS the ECM?????

[TustinTundra]

I hooked up an OBD II from Autozone, but I kept getting a "No Link" error. It would not give me any codes. Does anybody know what is wrong?

[mustang67408]

I hooked up an OBD II from Autozone, but I kept getting a "No Link" error. It would not give me any codes. Does anybody know what is wrong?

AUTOZONE needs a better tester.