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P0031 after replacing all 4 O2 sensors, EGR, plugs/wires/coil
Modified JK TechTech related bulletin board forum regarding subjects such as suspension, tires & wheels, steering, bumpers, skid plates, drive train, cages, on-board air and other useful modifications that will help improve the performance and protection of your Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) on the trail.
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I appreciate the schematic, I have a question. If I’m looking at this right the heater ckt and sensor ckt are separate right? If that’s the case then when they say that an open would give you a high indication are they talking about on the signal side or heater side?
Interesting question! Connector disconnected, as mentioned earlier i believe it should read high. Sensor circuit open, same -- floating high. Now for an open heater circuit, which will set a separate DTC for heater circuit high, I believe it will be something above 2.52 volts based on the criteria for P0131 O2 sensor circuit low:
P0131 O2 sensor circuit low
When Monitored:
Engine running for less than 30 seconds and the O2 Sensor Heater Temperature is less than 251 degrees C (484 degrees F) with battery voltage greater 10.4 volts. Set Condition:
The oxygen sensor signal voltage is below 2.5196 volts for 6 seconds after starting engine. Two Trip Fault. Three good trips to turn off the MIL.
Yes with 1-1 disconnected I still get a high with the scan tool. I do not know why when it is connected I get misfires. I going to find a schema for all 4 sensors, maybe there is a common connection point or route the harness takes that could of opened?
Mr. T I seem to of missed some of your questions. I’m using a fluke meter to take all my readings. I have a scan tool to read the fault codes and reset them. That’s about the extent of its capabilities. Would you know where I could get a full pin out for the second connector on the PCM?
I took reading on the C2 connector. Between c18 and C31 I had 0 ohms. Both C18 and C31 go to the same pin on the connector between the harness and sensor.
I took reading on the C2 connector. Between c18 and C31 I had 0 ohms. Both C18 and C31 go to the same pin on the connector between the harness and sensor.
If I understand, C2/18 and C2/31 are shorted, measured at C2 toward the 1/1 O2 sensor (not the PCM). The way I'm denoting this is Connector/Pin, so C2/18 is Connector C2 pin 18. This is all per the O2 1/1 schematic above.
But here's where I'm confused, C2/18 goes to pin1 at the 1/1 O2 sensor connector (heater +) and C2/31 goes to pin 4 at the O2 sensor connector (O2 1/1 signal). With the sensor disconnected (or connected), the resistance should be infinity between these points regardless of whether measuring at C2 or the O2 sensor connector (and I'd do it both ways). If it's actually shorted, the wiring is bad -- very uncommon but possible if critters are munching on them.
You could really benefit from getting some type of scan tool or software that can read values from the PCM. If you have a laptop, the Appcar DiagFCA software with an OBDLink MX+ bluetooth adapter (includes OBDwiz graphing software) is very capable. There's others too, I did a review in a recent post you can search for. Knowing how to use a meter is great, but often it takes knowing what the PCM is actually seeing, and starting there is a lot easier/faster.
This only matters if you're doing key-on voltage measurements, but Chrysler/Jeep usually has a bias voltage on the O2 sensors. With a 2.5 volt bias -- Measure 3.0V with a meter and OBD2 software like HPTuners will show 0.5 for sensor volts from the PCM, but there could be a scanner tool or software that include the bias and display the raw 3.0V.
On of my favorite methods using a voltmeter is to use a sewing needle to pierce the insulation, and attach the meter lead to the needle for in-circuit measurement. When finished smear some silicone sealer where the needle was.
Haven't found a pin-out the C2 connector, will take another look.
Last edited by Mr.T; 08-17-2019 at 09:14 AM.
Reason: typo
08-15-2019, 08:29 PM
