[Q] Driving without O2 Sensor ('97 Honda Civic)

Hi all,

I have a '97 Honda Civic LX (auto, 1.4 EFI). I recently had a
front-end collision, and after I got the car back from the body shop,
I found out that an oxygen sensor had one of its wires cut, presumably
from the radiator bracket that was pushed it from the collision.

The problem for me is that I have to wait two weeks before I can have
the sensor replaced because of some bureaucratic mess at the insurance
company. Driving the car as is, I'm experiencing a sudden drop in rpm
or no revving up or accellation with the pedal down, especially when
the engine is hot and driving on freeways.

My question is whether I can disconnect the oxygen sensor for now
until I get it replaced without doing any major harm. FYI, I believe
Civic has two O2 sensors, and it is the one mounted near the exhaust
manifold that is broken on mine. The one below the catalytic converter
seems okay.

Two additional questions:

1. Why didn't the malfunctioning O2 sensor register in the computer
module? I don't have a scanner, but the check-engine light is off.

2. Why am I getting such a wide range of quotes for an O2 sensor? Even
at Pep Boys, one store quoted me $46, and another $300+!!!

Thanks in advance.

-Roger
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I recently replaced my O2S as well, and found the same price variations
you found. The sensors I got quoted fell in three categories:

Honda original Expensive
Bosch replacement with Honda type connector Moderate
Bosch replacement with generic connector Cheap ($70)

I do not know how smart the ECU is. My O2S has 4 wires, two for the
heater and two for the sensor itself. On mine the heater broke (not the
sensor), and it is simple for the ECU to detect this break. I do not
know if it can detect a failed sensor.

Without the O2S the engine will not properly regulate the air/fuel
ratio. I don't know how well the ECU handles a failed O2S, but if you
drive with too rich a mixture you could overheat and damage the
catalytic converter.

If you disconnect the O2S, the ECU should detect it and default to a
fail-safe mode of operation. I would imagine that it is OK to drive like
this for a week or two.

 

My 97 Civic also didn't detect when the O2 sensor plugged up enough that
the car ran badly. This could be related to the Honda's OBD tampering
that got them busted by the EPA and CARB.

Disconnect the sensor and drive the car very gently. You don't want to
melt out your catalytic converter. Better yet, buy a new one and get
reimbursed when your insurance company gets it's crap together.

 

Some times ago Honda only use feedback from O2 sensor in the idle mode. The
rest are open loop. Since when Honda start using feedback from the O2 sensor
during power mode?

 

Thanks to all for the replies.

A few follow-up questions:

1. Is it better to replace the other O2 sensor at the same time? If
so, are the two sensors a same type (interchangeable)?

2. If I were to drive with the broken O2 sensor disconnected, should I
disconnect the other as well?

TIA

 

I believe that the sensor has an on/off characteristic: any variation
of the oxygen content from ideal sends the sensor into saturation. I
think most ECU's do a sanity check: if the sensor never changes state,
especially with wide variations in mixture, they flag an error.

<snip>

 

97 started OBD 2. Your Honda should be setting a code for a "Cold" O2
sensor. If the O2 sensor has more than one wire coming from it then it is
heated. If it was one of the wires for the heated side of the sensor that
was broken, then the ECM may not set a code. Another possibility is that
your engine isn't getting warm enough to signal the ECM to start accepting
the info from the O2 sensor. This would be caused by the fan being on all of
the time, the coolant sensor is inop or the thermostat is stuck. In theory,
a low temp should set a code but Honda was one of those "Special" cars that
doesn't have standards!