I bought a new ODB2 reader and I was testing it out on my 2003 Infiniti I35. I noticed that there are 2 codes even though the check engine light did not come on. But codes were P1800. I had to deal with this same code 4 years ago and it was quickly fixed after replacing it with a new Intake Manifold Runner Control Solenoid Valve from amazon. So naturally, I repeated the same fix this second time around. I tried erasing the code using a scanner but as soon as the code is erased, it comes back again. I am hoping that if I keep driving it, the code will eventually disappear.

I just replaced my timing chain tensioners and a whole bunch of stuff on this car, and it seems to be running great. Any thoughts on how to make the P1800 code go away?

 

Just wanted to share my learnings in case others run into the same problem of not being able to get rid of P1800 code even after replacing intake manifold runner control solenoid valve.

Upon closer examination, I noticed the tubing that I replaced several years ago are now brittle and may not be holding a vacuum. I decided to get some high temperature silicone tubing 5/32 inch. These are made to withstand engine heat unlike the cheap rubber hoses that I put in a few years ago. After putting in the new silicone hoses, I was able to erase the P1800 code and it never came back - finally. So I guess in addition to a bad valve, I probably had leaky hoses.

 

good to hear! i was gonna suggest you check your hoses as well!