'91 Civic DX, throwing ECU code 12
#1
08-01-2010, 08:17 AM
'91 Civic DX, throwing ECU code 12
G'day 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.
Can someone please give some suggestions as to what to look for?
Cheers,
Norman C
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.
Can someone please give some suggestions as to what to look for?
Cheers,
Norman C
#2
08-01-2010, 08:49 AM
The California version will have an EGR valve on top of the intake manifold near cylinder #4. The other 49-states version does not have an EGR system; it has a different ECU where code 12 would be impossible on those. Someone may have been switching parts around. Sticker on the hood will say California or not, if it is still the original hood. Do you have a plug for the EGR valve (3 wire) not going anywhere?
#3
08-02-2010, 06:10 AM
Yes, it is a California car and, yes, there is some question as to the originality of the existing intake manifold configuration. By this I mean, the existing manifold has no mounting point for the EGR, and from what I have learned recently, the California car manifolds should have this feature; thus, my not being able to locate the EGR valve! It is all beginning to make some sense to me. I need a manifold and the EGR valve to make this a usable, smog compliant car.
Thanks!
Thanks!
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