Couple of codes, how to fix?

[hulk311]

My 4runner has been running really rough lately, even when idling, the whole truck shakes very badly. I got two codes and would like to know how to fix them:

P0302 Cylinder 2 misfire

P0141 O2 Sensor heater circuit malfunction

 

[004Gunner]

I would get the cylinder 2 misfire fixed first. Check the spark plug first or just replace all the plugs if you have more than 30k miles on standard plugs, 60k for platinum, or 90k for iridium. If the problem persists then you will need to swap coil packs and wires to rule out ignition issues. The P0141 can be the rear O2 sensor which typically goes bad around 100k -150k miles anyway.

 

[hulk311]

Thanks for the info, where in the back is the 02 sensor and how much for a new one?

 

[004Gunner]

You'll see the rear O2 after the cat, or cats, and iirc it is aligned with the rear passenger door on the passenger side. I got mine from partznet.com but you can probably find it cheaper than the $110 I paid. I would recommend you get replacement nuts and PB blaster too since the originals will be rusted to hell.

 

[hulk311]

I replaced the O2 sensor so that code went away.

I also replaced all spark plugs and all spark plug wires. Truck ran fine for a day and now I have the CYLINDER 2 MISFIRE code again and code P0171: SYSTEM TOO LEAN BANK 1.

What else do I need to do to fix the misfire problem and how do I stop it from running too lean?

:bash::shrug:

 

[004Gunner]

You need to swap the coil packs and see if the misfire follows. I believe the #2 cylinder shares a coil pack with #5.

 

[greasefingers]

I would clean the MAP sensor

 

[hulk311]

Where is the MAP sensor?

 

[byrnes]

Did you ever resolve the #2 misfire issue? I'm having the same prob. Haven't cleaned the MAP sensor yet, did you find out where/how to do that? Thanks. -Bill-

 

[byrnes]

Now I've cleaned the MAP and throttle body, ran and idled great on the test run, then the CEL came back on and it's running like crap. P0302. It's gotta be the #2 fuel injector gone bad.

 

[byrnes]

That was it. Used a long 3/8 extension as a stethescope and all accessible injectors ticked like a purring kitten except #2. R2'd it and she runs like a dream!

 

[lekiboy]

Where is the MAP sensor?

hi,

am having hard starting issues and i would like to clean this MAP...please please post a pic on where can i locate this sensor...

all the best!