mike_s

I am getting a 0510 (P0138) ECU code - Downstream oxgyen sensor maximun voltage fault. What can cause this error code? a problem with the downsteam sensor or the upstream sensor or ?????

Thanks is advance for your help.

Mike

scottcameron

yah, I've had the same code since I bought my car over 3 months ago. However the downstream O2 sensor just monitors how the cat. converter is working and will not affect performance and I don't think it will affect even gas mileage but I'm not sure. You need to replace the O2 sensor which is after the cat. to fix your SES light though.

mike_s

Thanks for the quick reply.

The way I was look at it that the I'm getting a rich exhaust and since, as you mentioned the downstream O2 sensor just monitors the cat. and the upper has an affect of air/fuel mixture, I thought I might have a problem with the upper O2 sensor. Don't want to spend the bucks on a lower sensor to find out it was the upper one or something else.

Thanks again