jss43

I have a 1996 Civic LX, bought used with just under 80k miles on it. Before the codes nothing felt wrong with the car. When the CEL came on, I was driving in 1st gear <15mph.

Right when the light came on, all of a sudden the speedometer needle went erratic, at idle it would jump up to 20mph randomly and one time it pegged 120. The instrument cluster lights were also slightly fading in and out.

Pulled the OBDII codes and got these codes:

P1298 Manufacturer Fuel-Air Meter Malfunction
P0135 o2 sensor heater malfunction, bank 1 sensor 1
P0141 o2 sensor heater malfunction, bank 1 sensor 2

What could have caused these codes? I saw in a FAQ that the P1298 was listed as something else, Electric Load Detector (ELD) Circuit High Voltage, but my Actron CP9135 gave a different description. Has anyone ran into these codes before? Is there any way to test the questionable parts?

Edit: I searched some diagnostics for o2 sensors and checked the heating element. The front heating element impedance measured is 13.9 ohms, rear impedance is 13.4 ohms. I haven't checked to see if there is power coming from the relay going into the heating element yet. Do I have to turn the engine over or can I put the key into the 2nd position and test it?


Modified by jss43 at 4:02 PM 10/4/2004

mrek

i ran into both o2 sensor problems, but it was just the sensors, the only solution was to replace the sensor. the heater circuit does what is says heats up the sensor so it can get a proper reading, i dont know what could have caused this, but i do know when i hit the two o2 sensor codes i replaced them and that was the end of that.

jss43

So you replaced both the front and rear sensor? I'm a little confused on the bank 1 comments on the trouble code but it does say sensors 1 and 2, but my main concern is buying new sensors and the same problems occur.

Also, is it common for both o2 sensors to go bad at the same time? I thought usually only the rear one goes.

Edit: I searched some diagnostics for o2 sensors and checked the heating element. The front heating element impedance measured is 13.9 ohms, rear impedance is 13.4 ohms. I haven't checked to see if there is power coming from the relay going into the heating element yet. Do I have to turn the engine over or can I put the key into the 2nd position and test it?


Modified by jss43 at 4:02 PM 10/4/2004

jss43

any other experiences/thoughts?

EE_Chris

Sounds like you may have blown a fuse considering that the O2 heater elements are in good condition.

Check Fuse 15 (7.5A) in the under-dash fuse box.

jss43

Checked fuse 15, it was bad. So I replaced the fuse and it blew again, so I'm guessing there's a short somewhere in that circuit. I'll try to trace it out, but if anyone has the wiring diagram it would help me out a lot.

jss43

bump

cgincovington

I just had this problem with P1298 and P0141 codes. I found the wires for the secondary o2 sensor were contacting the bracket that holds the connector. The connector had wandered off of the bracket. I wrapped the wires with electrical tape and better secured the connector to the bracket. All better.