Maf, 02 and knock sensor codes. Am at a loss!!

[95se]

I have a stock Ka with injen intake with 200K on it. Just got car back from body shop after basically a complete restoration. Car was running extremely rough and check engine light came on. Mechanic said it was maf and knock sensor codes and the knock sensor always is dummy code by nissan that is thrown anytime any other sensor throws a code. Tech said the maf was all over the place on the graph so they swapped it out with another duralast one with lifetime warranty. He also replaced fuel pump, filter and plugs. Car runs better now but check engine light came on again after 10miles driven and engine slightly cuts out and idle is slightly rough. So had it scanned at autozone and now its the 02, Maf and knock sensor codes. I just replaced another Bosch 02 back in Nov. I have replaced the 02 sensors about 4 times in last 14yrs but the Maf's started giving me problems back in 2013. Another shop fixed a small ground wire from engine to wire harness then put in a used maf which lasted about 6 months then it threw the code and put in another used one which lasted 8 months then back in last May then another cel was set off by maf and finally put in a new one from autozone with lifetime warr and new k&n filter. Then after the car being in the body shop since Dec replaced the maf again. The tech said he hooked it up to computer and ran diagnostics on it after the new one was swapped in but didn't find anything. So I am at a lost at this point. The mafs started having problems in the last 3 yrs but the injen intake has been on since 2000. This is the first time when maf and o2 codes were set at the same time.

[jedi03]

How's your battery?

[95se]

The car starts fine so battery is ok. Why would the battery have anything to do with codes being sent...

[Kingtal0n]

0: set or verify ignition timing is correct
1. tune up filters/plugs/pcv valve/wires/rotor/cap/etc
2. boost leak test to find all leaks , compression test the engine for good measure
3. inspect wiring / check continuity to the ECU using an FSM to guide you

4. if 1-3 fail, replace the parts in question using known good USED parts from a known good donor RUNNING vehicle.

5. FWIW I've never checked a code on any car made before 2003 and diagnostically they are very simple, i.e. with respect to the maf: if there are no leaks and the sensor is good and the wiring is good all that remains is the ECU itself, regardless of whatever "codes" you see, use common sense.

[95se]

They replaced maf, fuel pump and spark plugs and I put in O2 sensor back in Nov. Fan clutch and power steering pump were also replaced in Nov right before it went to body shop. I know those two things would not have anything to do with the codes being thrown. Though, for some reason the fan clutch is working better but it still has that whining noise for the first 30 secs which it never had before. Also, kind of sounds like there is a slight droning noise.

Could a bad connection somewhere actually damage the Maf? Up until this point when I have replaced it after it throwing a code the cel wouldn't not come on for several months so I assume they were actually damaged. The output of the computer has been ok when they have checked it. So I don't know.