I have a 2002 Nissan frontier with approx. 260kmiles. it's time for smog and the person that did the check told me there was a spacer on the end of my o2 sensor and to have my mechanic remove it. I had no check engine light or any other issues during the test. it was just the spacer he failed me on.
I took my truck to my brother (found a good deal for a set of o2 sensors on amazon for $40). He replaced both sets of o2 sensors and removed the spacer. Now I get a check engine light with a P0037 code. I checked the fuse (it looked good) and he said the wiring is fine. The only other thing that shows via online searches is the PCM. I'm not familiar with this nor how to troubleshoot. any ideas?
found a good deal for a set of o2 sensors on amazon for $40
There's your problem, or at least one of the problems. Amazon is notorious for counterfeit parts and poor quality Chinese knockoffs. You can't expect your "good deal" cheap O2 sensors to work properly. You need to install OEM sensors. It's also possible that wiring was disturbed while installing these "bargains". See the links below for possible causes of P0037.
https://www.obd-codes.com/p0037
Of course you may have other problems. Typically the reason a spacer is installed on a downstream O2 sensor is to mask a catalytic converter problem.
sensors on amazon for $40)
you get what you pay for unfortunatley, but like Chuck (and Scotty in the video below) said make sure do try some basic troubleshooting first before running out to buy parts.
https://www.youtube.com/watch?v=svDzJMEnVD0
I took my truck to my brother (found a good deal for a set of o2 sensors on amazon for $40)
Amazon drivers don't really care about stuff they deliver, even if they were the original equipment O2 sensors. I bought a genuine AC/Delco brake master cylinder when I was buying my Pontiac 4 years ago from Amazon, bench bled it, bled all 4 brake lines, farthest to nearest to the master cylinder, the usual. The brake pedal was solid, so I started the car and pressed the brake again. It held for a split second and then went right back to the floor. It took me 3 brake master cylinders before I finally got one to not give up the ghost as soon as I started the car. All 3 times I got out of the car to look at what went wrong, brake fluid escaped from in between the cylinder and booster on all 3 of them.
