Check Engine Light: 2003 8.1 GM

[boboaks]

I have 2003 Mountain Aire with GM8.1 Workhorse engine. The check engine light comes on and the coach goes into limp mode immediately. Scan shows heated oxygen sensor. Surprised that it goes into limp mode for sensor. Has anyone seen something similar? I can disconnect and reconnect battery and it will run fine for sometimes 40 miles or 200 miles before it happens again.

[wildebill308]

57 minutes ago, boboaks said:

I have 2003 Mountain Aire with GM8.1 Workhorse engine. The check engine light comes on and the coach goes into limp mode immediately. Scan shows heated oxygen sensor. Surprised that it goes into limp mode for sensor. Has anyone seen something similar? I can disconnect and reconnect battery and it will run fine for sometimes 40 miles or 200 miles before it happens again.

Have you tried changing the oxygen sensor? 

By the way welcome to the forum.

Bill

[boboaks]

Am in process of changing. Was surprised that the sensor would send it to limp mode.

[zorro2kita]

Have you cleaned your Mass Air Flow Sensor ?   How long have you owned coach ?  How many miles on coach ?   Which O2 sensor is failing ?  I've experienced limp mode -  not a pleasurable experience !!

[dickandlois]

2 hours ago, boboaks said:

Am in process of changing. Was surprised that the sensor would send it to limp mode.

The reason you can get the engine out of limp mode when you disconnect the battery is the ECM memory is erased and the engine needs to run for a period of time for the ECM to read all the sensor information and if the 02 sensor voltage is out of range or the MAP sensor is not reading the proper air flow - it will go into limp mode > the MAP - Mass Air Flow sensor tells the ECM what the fuel mixture for the load should be - So if the fuel mix is rich or lean the engine will go into limp mode. This is to protect the engine from serious damage if the mixture is to lean, one can damage the pistons and valves.

Rich.

What codes does the garage or someone else get from your ECM ? 

[boboaks]

The code read "P0131 Heated Oxygen Sensor Bank 1 Sensor 1"

Have 36,000 miles. Have not cleaned Mass Air Flow Sensor. Owned the coach since 2012. Had a Banks system installed in 2016.

[dickandlois]

Thanks Bob, Hot 02 sensor, kind of make me lean towards the engine also running on the lean side.

So it might be a good time to change the air filter, clean or replace the air flow sensor and take a look at a couple spark plugs to see what the gap looks like.

Good luck and let the group know what things looked like and how everything turned out.

Rich.

      Interesting that the number one Ox sensor went - the number 2 Ox sensor on my 8.1 is the one that shows up. from time to time - but mine does have 145,000 miles on it. I call it my over sized Vet. The only thing it will not pass is a gas station. LOL

[boboaks]

Thanks to you all. I am changing O2 and mass air sensors. Will check plugs and will update.

[boboaks]

On 8/14/2017 at 0:28 PM, DickandLois said:

The reason you can get the engine out of limp mode when you disconnect the battery is the ECM memory is erased and the engine needs to run for a period of time for the ECM to read all the sensor information and if the 02 sensor voltage is out of range or the MAP sensor is not reading the proper air flow - it will go into limp mode > the MAP - Mass Air Flow sensor tells the ECM what the fuel mixture for the load should be - So if the fuel mix is rich or lean the engine will go into limp mode. This is to protect the engine from serious damage if the mixture is to lean, one can damage the pistons and valves.

Rich.

What codes does the garage or someone else get from your ECM ? 

 

On 8/14/2017 at 2:59 PM, boboaks said:

Thanks to you all. I am changing O2 and mass air sensors. Will check plugs and will update.

I changed O2 and mass air sensor and have not had any issues since.