I have a 2000 Accord LX with a 2.3L 4-cylinder VTec, manual transmission, before I purchased it, the previous owner replaced the exhaust from the headers back, so I have one oxygen sensor plugged in now, whereas I should have two. The plug for one of them is just dangling with nothing attached to it, which of course is throwing a bad reading, which is causing my fuel-air mixture to be off lowering my gas mileage. This car has several problems costing me fuel mileage, so I'd like to break them down one at a time and fix them so as to help improve gas mileage and engine performance. If anyone on here knows what the voltage that the computer needs to get back from oxygen sensor to show the reading is normal please let me know, I plan to build a resistor to plug into the oxygen sensor connection to trick the computer into believing the oxygen sensor is there and giving a normal reading. Thank you for your help.

Pamela
TechTinker

 

I think it's more complicated than that. It'll want to see about 1v DC, but I think it also wants to see fluctuations that correspond to what it's doing with fuel control.

You could have a sensor bung welded onto the exhaust?

AFAIK, the 2nd sensor (back in the cat) doesn't do anything to fuel control. It is only there to measure whether the catalyst is working OK. The 1st sensor (in the exhaust manifold) has some authority to modify fuel rate. So if you're looking for something causing bad fuel rate, that won't be the rear O2 sensor.

What error code is it throwing?

 

O2 sensor is in pipes before first flange. No rear O2 sensor at all, no Cat at all. I've attached a list of codes from my Bluetooth obd2 scanner. I just replace the electronic load detector in the fuse box under the hood, then cleared all the fault codes, but these keep coming back.

 

P0131 primary O2 sensor low voltage

P0500 VSS vehicle speed sensor

P1298 ELD high voltage - you changed it & this still comes back?

P0325 Knock sensor circuit problem - I think the knock sensor is on the back of the block below the intake manifold?

P0171 system too lean - measurement by primary O2 sensor

P0141 secondary O2 sensor heater circuit
This is the only one related to the rear O2 sensor, and it's the heater circuit. The connector that's hanging has 4 wires. Measure between BLK/WHT and BLK/YEL when the ignition is turned on - should be battery voltage. If so, connect a resistor there between 10 & 40 ohms. Not sure of the power level. That's your substitute for the sensor heating element.

 

Yes I replaced the eld & the same code is coming back. I knew speed sensor was bad, the speedometer doesn't work. But the primary O2 sensor needs replacing? Just under the distributor is a plug in something that is broke off. I was thinking it was the speed or knock sensor, but I haven't check yet. I'll post a picture in a few

 

With so many trouble codes at once, it may be due to a blown fuse. Check Driver's side under-dash Fuse No. 6 (15A) first.

 

It's good, was blowing one a day, until I changed the eld under the hood.

 

Driver's side under-dash Fuse No. 6 is directly related to the VSS, ELD, Primary and Secondary O2 sensors. Measure the voltage at the Blk/Yel wires going to those components.

Ignition switch in the ON (II) position. Car not running.

 

The rear O2 sensor wold give a code PO320. It also (like Jim mentions) that the cat convertor is doing it's job. It'll run with it missing, but it'll throw a code.
You really need the front one plugged in, as the ECU is looking for readings from it to adjust the fuel mixture and timing.
Like mentioned above, I'd put a bung in the exhaust (use a spark plug anti fouler) and put the rear sensor in it.
You might want to clear the codes, and see which ones come back.

 

the front one is plugged in, I cleaned the IAC valve due to unusual idling, with spikes in rpms ranging from 1200 to 2400, that seems to have calmed it down. I also replaced the VTEC solenoid gasket which has stopped my oil leak completely it seems. I still have one or 2 hoses that will need replacing due to prolonged exposure to oil. Is a knock sensor a neccesity? My car is weak as a kitten, & often times I'm only idling at 400 rpm. It causes my headlights to dim at night & so on. I can see the voltage made by alternator rarely drops below 14, so I'm pretty sure it isn't the alternator.