Code 21 & 71

Discussion in 'Engine/Drivetrain' started by 93TILinfinity, Apr 9, 2014.

  1. 93TILinfinity

    93TILinfinity Veteran

    Joined:
    Mar 13, 2014
    Messages:
    305
    Likes Received:
    3
    Location:
    Lake Elsinore, CA
    Truck:
    1993 Toyota pickup 2wd 4cyl 5speed cab and a half standard bed
    I tried searching this but had no luck. I had some doug thorley headers, no name aftermarket cat and a flowmaster 60 series installed with 2.25 inch piping. The check engine light is now on. Had my neighbor check it out said it's a code 21 71. If he is not mistaken he said 21= o2 and 71=egr. Why did this occur? What can I do to check this out & fix this? Has this happened to anyone else after installing exhaust? Anything helps thanks in advance.

    Ps: i live in California where they are strict on emissions
     
  2. kamesama980

    kamesama980 Addict

    Joined:
    Jun 28, 2010
    Messages:
    511
    Likes Received:
    1
    Location:
    Columbus, IN
    Truck:
    91 Base
    O2-probably damaged the wiring. Might have poisoned the sensor with rtv, paint fumes, dirt, ???? use the troubleshooting flowchart to check it.

    EGR I'm kinda surprised since last I checked, Toyota just used a temp sensor to see if hot gasses are going through the EGR passages. On the other hand, EGR flow is dependant on the pressure differential between the exhaust and intake manifold. If you alter that ratio (by changing exhaust flow-rate) you alter EGR behavior. Any of the passages getting plugged up, blocked off, or otherwise altered will change behavior as well.
     
  3. 93TILinfinity

    93TILinfinity Veteran

    Joined:
    Mar 13, 2014
    Messages:
    305
    Likes Received:
    3
    Location:
    Lake Elsinore, CA
    Truck:
    1993 Toyota pickup 2wd 4cyl 5speed cab and a half standard bed
    Where can I find this chart?

    I'm going to upgrade the manifold gasket to and aftermarket one. Hopefully that's the issue.
     
  4. Malessohomegrown

    Malessohomegrown Toyotaholic

    Joined:
    Mar 16, 2011
    Messages:
    1,282
    Likes Received:
    4
    Location:
    Malesso,Guam
    Truck:
    87Hilux,92Hilux reg,914x4 HiluxEC
    Do the doug thorleys have the o2 plug anywhere on them and if so is was it connected after the swap.There are two on the stock set up.Here on Guam we don't have emissions so we don't have to worry about it but if you swap out your headers and don't plug in the 02 sensor it will read code 21.In the past I have found where the wires had touched the exhaust and melted together and it gave a code 21.
     
  5. 93TILinfinity

    93TILinfinity Veteran

    Joined:
    Mar 13, 2014
    Messages:
    305
    Likes Received:
    3
    Location:
    Lake Elsinore, CA
    Truck:
    1993 Toyota pickup 2wd 4cyl 5speed cab and a half standard bed
    It's not on the headers it's just before the cat and right after. I might just swap out the o2s see if that helps
     
  6. Malessohomegrown

    Malessohomegrown Toyotaholic

    Joined:
    Mar 16, 2011
    Messages:
    1,282
    Likes Received:
    4
    Location:
    Malesso,Guam
    Truck:
    87Hilux,92Hilux reg,914x4 HiluxEC
    So how did you run the o2 sensor that's closer to the motor back to the cat.Extended the wires?
     
  7. 93TILinfinity

    93TILinfinity Veteran

    Joined:
    Mar 13, 2014
    Messages:
    305
    Likes Received:
    3
    Location:
    Lake Elsinore, CA
    Truck:
    1993 Toyota pickup 2wd 4cyl 5speed cab and a half standard bed
    That's the one I ment before the cat my bad. But no it's right where it is suppose to be about a foot or so from where the headers start
     

Share This Page