Error Code 12, Rough Idle When Warm
 

Looking for input, please. I have a 1995 Toyota Camry DX with 192k miles. I have a check engine light with Code 12 (checked it myself with a jumper, then had a shop verify). From what I understand the car shouldn't be running with this code, but it is and has for about 2-3k miles. I have replaced the plugs (pre-code), wires, distributor cap and rotor, and Engine Coolant Temperature Switch. I had the timing belt/water pump replaced last week. The car runs fine until it heats up, then it is very rough at low idle. As long as you are in the throttle there are no problems. I tried cleaning the Air Idle Control Valve (not sure how well). I really don't want to just start throwing a lot of high dollar parts at it until I fix it. Does anyone have any suggestions as to where I should start? Thanks for your help!

P.S. When I say rough idle, I mean it acts like it wants to stall. RPM's are erratic.

The code is for the pickup coils inside the distributor. Did you replace this?

Check coil wires as follows:
G1-G Cold 125-200 ohm, Hot 160-235 ohm
G2-G Same as above
NE-G Cold 155-250 ohm, Hot 190-290 ohm

Electrical terminal orientation on distributor plug.
G, G2, G1, NE

G is ground and will have a black wiring running to it.

Black, Red, Blue, Yellow

Also check ohm reading over a number of seconds as it may rise or fall slowly. If so coil is bad.

No, I haven't. Will replacing the distributor fix the rough idle problem? I bought a distributor today but haven't installed it yet.

Can't state 100%.

If Code 12, check resistance of the pickup coils in the distributor.

Check electrical wiring and harness plug for distributor.

Another possibility is the engine computer.

A engine can run with Code 12, but may be hard to start, idle rough, run different when cold then hot.

If it is a pickup coil then given there are not replacement parts, changing the distributor is the only route.

You can also use an ohm meter to compare readings between old and new distributor.

It was the distributor. I honestly don't know how the car was even running. I removed the distributor and there were copper windings wrapped around the distributor shaft, looked like a bird's nest. After replacing the distributor she runs great. Thanks for all of your help!
Jeff

Great job. Thanks for posting back with the fix.

Awesome! Thanks for posting update!