Best Repair/Replacement for O2 Sensor errors

[johnchmaj]

My 2003 Newmar Scottsdale with Vortec 4500 8.1L engine recently threw the following error code:



P0131

02 Sensor Circuit Low

Voltage Bank 1

Sensor 1


I see multiple threads on IRV2 indicating O2 sensors are a common issue with the old Vortec engines on a Workhorse chassis. I'm not sure what the most appropriate repair should be. Should I just replace this one O2 sensor, or is it likely that I'll continue to get such messages from the other Sensors? Is there value in just replacing all of them? Any guidance on what to do here to avoid issues like this in the future would be much appreciated!


John Chmaj
Sammamish, WA

[code2e]

Originally Posted by johnchmaj

My 2003 Newmar Scottsdale with Vortec 4500 8.1L engine recently threw the following error code:



P0131

02 Sensor Circuit Low

Voltage Bank 1

Sensor 1


I see multiple threads on IRV2 indicating O2 sensors are a common issue with the old Vortec engines on a Workhorse chassis. I'm not sure what the most appropriate repair should be. Should I just replace this one O2 sensor, or is it likely that I'll continue to get such messages from the other Sensors? Is there value in just replacing all of them? Any guidance on what to do here to avoid issues like this in the future would be much appreciated!


John Chmaj
Sammamish, WA

I wouldn't call failing O2 sensors a common problem. In fact, O2 sensors are a maintenance item. They wear out over time and mileage. Yours is 19 years old, unknown mileage.

An O2 sensor measures the amount of oxygen remaining in the exhaust. Too much indicates a rich mixture and too little is a lean mixture. The sensor needs to react very fast to maintain good fuel trim. As sensors age, they slow down, as yours likely has. The PCM (computer) has determined the bank 1 sensor 1 is likely a problem.

Bank 1 refers to the side of the engine where cylinder #1 lives. On your that is driver side. Sensor 1 refers to the upstream sensor, before the Catalytic Convertor. No reason to replace any others until they fail, unless you would feel more confidence. The bank 2 sensor 1 would be next in line. Any sensor(s) after the Cat(s) only test Cat efficiency, nothing to do with fuel trim. There may be either 1 or 2 O2 sensors after Cat(s) depending on how many Cat(s).

[yeloduster]

That vintage Workhorse W series has only the pre-catalytic converter O2 sensor. One on each side.

If there is a question about the O2 sensors you should replace them if you don't know their history. They aren't particularly expensive. I bought mine on Amazon. See this LINK.

If the O2 sensors have been in there for 19 years they may be difficult to remove! Really stuck. Amazon also sells removal tools but I don't remember the size needed. Maybe someone else on the forum can give you guidance about that.

[Arch Hoagland]

I was having P0131 and P0132 codes intermittently while climbing mountains.
I replaced both sensors....no help. It got worse during a trip from California to Salt Lake City. Couldn't go 50 miles without a P0131 or P0132 CEL.

Went to a shop in SLC and they knew what the problem was right away. They cleaned the MAF and I never got another CEL plus I gained a ton of power back.

They said they saw the problem a lot. So clean your MAF before you do anything else.

[code2e]

Originally Posted by Arch Hoagland

I was having P0131 and P0132 codes intermittently while climbing mountains.
I replaced both sensors....no help. It got worse during a trip from California to Salt Lake City. Couldn't go 50 miles without a P0131 or P0132 CEL.

Went to a shop in SLC and they knew what the problem was right away. They cleaned the MAF and I never got another CEL plus I gained a ton of power back.

They said they saw the problem a lot. So clean your MAF before you do anything else.

Cleaning the Mass Airflow Sensor is a good low cost idea. Also the air intake from the MAF to the throttle body could be checked for air leaks.

In your case, you had both O2 sensors setting codes. That would increase the chances of MAF issues to look into. In the OP's case, only one O2 sensor is throwing a code. Intake would likely affect both banks equally.

With the age of the sensor, 19 years, it's suspect from a wear standpoint and not expensive or hard to change. Another reply mentioned a tool needed. Usually a 7/8" box wrench will do most.

[Arch Hoagland]

There is a special tool to remove the sensor, well worth the money.

I soaked my sensors with PB blaster a day before I removed them.

Also there were a couple different sensors used that year and so I took mine to Napa to match them.

Initially I was just getting P0131 for the first year of intermittant CEL's. As time went on P0132 showed up.