I have a base model 1988 Honda Civic hatchback that I have been trying to resolve a Code 1 (Oxygen Issue) on for some time. So far I have done the following:
1. Replaced the O2 sensor
2. Replaced the main relay
3. Replaced the distributor, wires & plugs
4. Adjusted the timing

I'm still getting the pesky Code 1. I have measured the new O2 sensor and it is showing very low voltage (<.1v) which would indicate a lean condition. However, the car seems to run and idle just fine (which doesn't make any sense). I have to assume that the O2 sensor is good because I just replaced it so if that is the case, I have to look for other reasons that it would run lean. Looking at the forums I have narrowed it down to a clogged fuel filter, leaking vacuum lines or a leaking exhaust manifold gasket, Anything else it could be?

 

low fuel pressure or problem with the wiring

 

Back probe C16 at the ecu, should fluctuate between 0-1V. If its not fluctuating then something aint right.