My 2003 350Z is giving codes for P0031/P0037. Which are heater control circuit low for bank 1, sensor 1 and sensor 2, respectively.

I recently went in the shop because my car was stalling out at idle. Turned out I needed a new MAF sensor and a new TB. After replacing those, the mechanic couldn't set the idle, even through the ECU. It was sitting around 1200. I was getting a P0507 code, for idle control system. So I recommended an ECU replacement based on what I saw online. That fixed the high idle problem, but now I have these 2 new codes.

Any ideas??

 

Update: Car is in the shop now. The tech thinks that the Seafoam I used could have damaged the exhaust O2 sensors on Bank 1... I'm only getting like 17mpg, he said that is normal for a malfunctioning O2 sensor. Also, at 90K it's not a bad idea to replace your primary O2 sensors, his words...

I will post an update with the final resolution when I get her back.

 

Update 2: Turns out it was a faulty ECU. Used ECU for $300, and programing/install $200...

Check engine light free and running like a champ. . Thank you ZFever