Code 13 1990 PA, 3800 engine

Have been getting a lot of code 13 Oxygen sensor. I cleaned the orig, minor improvement, replaced with a used one with slightly better preformance but it still triggers a service engine light after about 100 kmph. Hey I should be happy. It's getting better. Most often it will cancel the light when slowing down and don't often see this in city driving. Guess it's off to the wreckers and grab a handfull of the darn things. :(

Is this a common problem?

TIA

If you had a scan tool, you could easily test the circuit to the ECM......

Common problem? Not really.....it's a 23 year old engine......by now, should have had at least two put in.......can be contaminated by a coolant leak, or a lean condition which would cause the engine to run rich and carbon up the sensor....

Putting in used O2 sensors is hit or miss.....

Single wire 02 about 23.00!!

With the O² disconnected, KOEO, check for a 450mV bias signal from the ECM at the O² connector.

With the O² disconnected, KOEO, check for a 450mV bias signal from the ECM at the O² connector.

My wrecker buddy suggested I try another EGR. Took it for a drive and the code never came up. (yet) :)

Measured the voltage as you suggested. I get 195 mv.

With the O² disconnected, KOEO, check for a 450mV bias signal from the ECM at the O² connector.

Follow up on the bias signal. I obtained a second ECM and again measured the voltage. With this box I get just short of 400 mv. How important is the bias signal voltage? I notice no difference in performance but haven't really tested fully yet. Will be hitting the highway tomorrow for a 1000 mile journey so should be able to get a fairly accurate mpg reading. I know my mileage recently certainly has deteriorated.

Follow up on the bias signal. I obtained a second ECM and again measured the voltage. With this box I get just short of 400 mv. How important is the bias signal voltage? I notice no difference in performance but haven't really tested fully yet. Will be hitting the highway tomorrow for a 1000 mile journey so should be able to get a fairly accurate mpg reading. I know my mileage recently certainly has deteriorated.


Update:
Have returned and results are much much better. My mileage this trip averaged just over 30 mpg. That's an improvement of about 5 mpg over the same trip in February. On previous trip the code 13 was on almost continuous. This trip not once! Both oxygen sensors test similar on the bnech but the code still came up. The EGR seemed to to be the culprit for the code 13. Which single item or was it a combination of all 3 items that are responsible for the considerable improvement in gas mileage?

My guess would be your ECM....

The ECM's in the earlier 3800's had some issues... some did 50k other did 150k..

Glad to see you are getting 30 Mpg.. With the 2.84 gears they can do a bit better than that..

If you buy a new sensor I would recommend looking for an AC Delco AFS-20..

Also if the MAF sensor has never been cleaned it may be due for a cleaning..

When I was driving my 91 Bonneville on the interstate I easily pulled 31 going well over the 70 Mph limit.. Miss that car..