jeem

Hi guys. I have a 2001 Civic SI with 330k and the car has a definate bog off idle and will only accelarate at full throttle. I receive obd2 code P0132 for the primary o2 sensor both before and after replacing that sensor with a new one. At operating temp the voltage at idle on the Pri o2 is 1.275v and on the Sec o2 is 0.055v. When the car is acting up...ie, "bogging", the voltage on the Pri o2 is 1.275v and 0.0v on the Sec o2. I have also once received a P0172 code, (system too rich), but always get the P0132 code. I'm thinking Primary Cat is clogged. All I know is that the engine bogs unless the pedal is matted to the floor. Any help would be appreciated.

ezone

Electrical problem.

What brand sensor did you buy? (it better be NTK or Denso)

P0132 is front O2 sensor high voltage......so find out why it's too high. It should be fluctuating between 0v and 1v, not above 1v when warmed up.


Are you getting the volt readings from a scanner data list?
Can you confirm readings with a regular voltmeter, backprobed on the signal return wire?
What is the O2 sensor voltage reading on the scanner with the sensor unplugged?
Connectors contaminated with liquid of any sort?
Lost grounding?

jeem

Thanks for the help. The sensor is a NTK and the connector is dry and makes good contact. What I have been able to determine so far is the there is no power on pins 3 and 4 of the harness that connects to the O2 sensor, the heater portion of the sensor, which I assume is fed from the ECM behind the glove box??? Btw, the new O2 sensor had a reading of 6 ohms. Also the voltage on the scanner with the O2 sensor unplugged remains at 1.275V. Also I have cleaned up the grnd wires located next to the thermostat housing. In any event the problem still persists and Im guessing the no voltage senerio coming into the sesnsors' heater circuit from the ECM is the issue???

ezone

That's a Canadian SI with a 1.7 VTEC and auto trans? (equivalent USA EX)

Measure voltage on the signal return wire for the sensor (white wire in the engine harness connector, not the sensor connector)
Green/yellow should be a ground

jeem

You're right except this one is a 5spd. I measured 12V on the white wire, (sig), on the chassis connector. That was measured between the neg of the battery and the white wire with key on. I get no voltage between the white and the grn/yel. Thanks.

jeem

So...after noticing that there was no voltage on the heater circuit for the pri O2 sensor I decided to take the car out for a test drive and noticed that when the engine was kept at ~3000 rpm or so, (ie keeping the sensor hot enough to operate), the car ran just fine. Originally I noticed this bog only when the car was cold started and sometimes driving while just bogging around trying to save fuel. The question is why is there no voltage on the heater circuit for that pri O2 sensor? It seems as though it is supplied from the ECM, so is the ECM at fault or are there certain ground locations for the ECM the one could look for. The O2 sensor heat circuit def has no voltage on it and when the car is driven at a higher rpm, heating the sensor it runs fine. Anyone???

ezone

If you connect a known good ground (like from the battery negative) to the white wire (O2 signal return)....the scanner SHOULD read zero volts.


Same result if you jumper the signal return wire (white) to the sensor ground wire (green yellow).

ezone

Connect your meter to battery positive and probe that wire, that way the voltmeter should read battery voltage if the wire is grounded.

OR Use ohms instead of voltage, meter leads on neg battery post and that wire, should show continuity or very close to zero ohms.

The green/yellow (sensor ground) is shared with several other sensors too, the other O2 sensor, TPS, ECT, IAT, EGR if equipped, so you could check continuity between the same color wire at any of those sensors and the same wire on the questionable O2 sensor

12v sounds high.

Unplug the bottom connector ("A") from the ECM and recheck with key on, voltage should be zero while ECM is unplugged.


With ECM connector A unplugged, make sure there is no continuity to ground and also no stray voltage on that wire.

ezone

I've seen primary O2 sensor fail in such a way that the ECM will either add or take away a whole bunch of fuel, enough to make the engine bog, but it doesn't last long enough to trigger a fault code.

IF there is a heater code set (P0135 for the primary sensor) I think the ECM quits trying to turn it on at all.


No 12v+ to the heater, or no ground to the heater? Gotta have both before the heater can work, and each originates in different areas.

If you are trying to check it with the sensor unplugged, it will not power up due to incorrect resistance and fault code set. Well, it should have 12v+ power but the ECM will turn off the ground as soon as it decides there's a fault....so the heater can't operate


Heater power originates at fuse #4 in the dash box, and is shared with the rear O2 sensor, EVAP solenoids, VSS, alternator, and some cruise control stuff.

Heater ground is controlled by the ECM. It is only turned on when the ECM decides to turn it on.


Got mice?

jeem

Thanks a lot for the information. I will look into all of these items, then prolly take it to a mechanic, lol. However don't forget that the original code I always receive, (rather than the 0135), is the 0132, the o2 sens h/v bank 1 sens 1 which when scanned at 1.275V. Is there something there affecting the h/v that I should be checking that may be affecting the way the engine bogs especially when cold? What is causing the h/v reading on the scan tool? It's kind of driving me crazy. Thanks a lot peops.

jeem

I need to go fire up my '79 'Stang 460ci stroker Ford Windsor....thanks a lot for all your' input EZONE, I appreciate the experience. Hopefully I can get this lil bitch Honda running ok before winter really sets in. Winter tires and rims should be bought instead of this unsuspected O2 deal. Oh, well $1100 SI, what can I expect. Hopefully I make it through the winter to Drag Race my 700+ HP Fox this coming summer. Stress sux, lol. Seriously, my first car at 15 was a '66 Lincoln Continental, second was a 1970 Javelin SST and on it went. Working on older cars is fun; I wish there were more of them and that fuel costs were what they were 50 yrs ago.
I know I sound like Frieburgler. Thanks again for the help.

ezone

You have P0135 too? Not set because the sensor was unplugged?



The threshold to set the P0132 code is when sensor output voltage reaches about 1.5v, so at some point it must fluctuate to reach that high.


Otherwise, The 1.2xx volts is being interpreted as a rich condition, so the ECM is continually attempting to reduce the fuel quantity injected to elicit a desired response from the O2 sensor output (it is trying to get sensor output to drop below the .45v switching point) and it can lean the mixture out enough to lose power and bog down.
(watch the fuel trim values when this happens, they are probably in the .7s or lower)

If the ECM can't gain control of sensor output through fuel manipulation, it may set the P0172 "too rich" code.

If you can find the root cause of why the the O2 sensor output is too high and fix it, the rest of the running problems should disappear too.