I have the code p0031, p0037 and p0051, p0057 on for each sensor. It says by the code, heater control circuit low. What would be the issue for me to get all four oxygen sensor codes? I was skimming through the troubleshooting manual but no way I'll be able to skim through 1300 pages to find the one I'm looking for. If someone can please throw me some ideas, that'd be wonderful. Thanks!