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ECU code 12, '91 Civic 1.5l

Discussion in 'Engine Tech / Drivetrain' started by Nortonfan, Aug 1, 2010.



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  1. Nortonfan

    Nortonfan New Member

    Joined:
    May 29, 2010
    Messages:
    7
    Location:
    Turlock, CA
    Hello to all,

    My ’91 Civic DX, 1.5L, Dual Point EFI, auto-trans, is throwing code 12 from the ECU. First, some history. I purchased this car about one month ago, and it had a blown head gasket, among other deferred maintenance. I removed the head and had it resurfaced, just to be sure it was flat. At this time gaskets, valve stem seals and necessary adjustments/repairs were performed. I replaced the thermostat, water pump, timing belt, misc. timing/drive belts, O2 sensor, ign. wires, plugs, dizzy cap and rotor, all rubber hoses and so on. I cleaned the IACV and replaced the PCV valve. I found the previously installed (old) PCV valve to be completely blocked. I ran the engine while still on jack stands for about two hours total, after which I changed the oil and filter. On its first drive following the above work, code 12 was thrown by the ECU, two blocks from home, even though it did not throw this code or any other while I tested it during the initial two hour run. I reset the ECU and it ran fine for another couple of blocks and threw the code again. I looked up this code in my Haynes manual and it tells me it pertains to the EGR system. I have searched for an EGR valve or whatever they use in place of it to no avail. All I have found is a cluster of relays and such near the firewall, on the passenger side, above the fuel filter.

    Lastly, after chasing each of the vacuum hoses to their respective connecting points, I noticed that hose 16 was disconnected and the end capped with a screw, which was just shoved in. I haven't a fog where this vacuum hose connects to. There is a cover plate held in place with two bolts, covering an opening on the cylinder head, near the distributor flange. Is this the mounting location for the EGR valve? There is nothing there but the cover plate at the moment. But I also don't see any additional (spare/disconnected) electrical connectors in the vicinity.

    Can someone please give some suggestions as to what to look for?

    Cheers,
    Norman C
     
  2. 2NRSTV

    2NRSTV Team Exile/ADO Garage Registered VIP

    Joined:
    Mar 29, 2010
    Messages:
    741
    Location:
    Monterey, CA
    Pics!
     
  3. EVIL_EF

    EVIL_EF New Member

    Joined:
    Aug 1, 2010
    Messages:
    5
    Location:
    auckland, new zealand
    code 12, EGR Lift Sensor (Exhaust Gas Recirculation) defective circuit or unplugged or defective lift sensor
     
  4. Nortonfan

    Nortonfan New Member

    Joined:
    May 29, 2010
    Messages:
    7
    Location:
    Turlock, CA
    Sorry,
    I don't have a clue how to insert a pic. I read the procedure and it is in geek speak which is completely foreign to me. I am very busy trying to resolve my car issues at the moment, and can't take time out to learn a new skill set.
     
  5. Nortonfan

    Nortonfan New Member

    Joined:
    May 29, 2010
    Messages:
    7
    Location:
    Turlock, CA
    Thanks for your response. I know the problem is related to the EGR system. As mentioned previously I did look this up in the Haynes manual, but I have idea where to look for the EGR valve. I've attempted to describe the only place the valve could have been mounted on the engine, but am not sure if the place I described is the correct placement of the EGR valve.

    Thanks again.

    Cheers,
    Norman C
     
  6. 2NRSTV

    2NRSTV Team Exile/ADO Garage Registered VIP

    Joined:
    Mar 29, 2010
    Messages:
    741
    Location:
    Monterey, CA
    Lol. It's cool about the pic. This is the best pic I could find about what you are looking for. This is your intake manifold. Number 15 is your EGR.
    If you are looking at your engine while standing at the front of your car. The EGR will be mounted on the far left Intake Manifold Runner.

    [​IMG]
     
  7. Nortonfan

    Nortonfan New Member

    Joined:
    May 29, 2010
    Messages:
    7
    Location:
    Turlock, CA
    Thanks! This helps a lot! I can see exactly what parts are missing from my car. The only difference I see is that my intake manifold does not have provisions for mounting the EGR as shown in the diagram you provided. Perhaps the manifold I have is from a non-California version of this engine, thus, no EGR mounting point. In any case, the information you have supplied is of great help. I should be able to source the required parts from pick & pull to make it work.

    Cheers,
    Norman C
     


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