Background: I’ve been using the Bosch oxygen sensor’s from Advance Auto Parts for my Elantra and Tiburon. Both had the same codes, after replacing the front oxygen sensor with a OEM one on the Elantra, the code went away. I bout a OEM front oxygen sensor for the Tiburon, but needed to extend the wires four inches or so. The same issue is persisting.
I attempted to solder the wires together the best I could, but being that they were Steel, it wasnt happening. There are only four wires, three of which are the same color, black, grey, and white. I went wire for wire, assuming nothing would be an issue.
Is it possible to switch the two heater circuit wires and have the same issue. Apparently the car will only heat up the oxygen sensors for the first minute of run time. I’m at wits end on this one.
Help!
well 135 is sensor heater. You can’t screw up the heater wires. Worse case, you can figure out what the car needs and run a resistor to trick the ecu into thinking its working.
The 131 is low voltage… have you used a scan tool to view the o2’s output? Is it swinging correctly?
Well, the issue came back today. I’ve checked my ODBII software, and I am getting no voltage out of the primary sensor. I’m thinking one of the wires must be goofy.
you have no power to it? or signal power coming out? could be wiring for sure.
OK, lets get alittle more in depth and try to fix my problem. Originally, when I bought the car from the previous owner, the secondary oxygen sensor was spliced into the wiring for the primary oxygen sensor. It was spliced in on the sensor side, and not the ECU harness side.
I’ve used both Bosch replacement and OEM sensor’s with the same two codes. I finally got more in depth and got out my ODBII software from Jay-M. At idle, the car is reading 0.1-0.475. When I start to drive the car the voltage will drop to 0 and stay there. I compared results from the Tiburon to the Elantra.
The Elantra will fluctuate between .475-.715, and around the same while driving. The only other problems I can figure out is either the ECU has a bad circuit board on it or there is a wiring issues. I have to get out the trusty multimeter and check the harness side for voltages, but this is driving me INSANE.
HELP!
I checked the Ohms on the heater at room temperature, and it was 2.6. HMA states as long as it’s under 30 Ohms at 750 degrees or under it should be fine. I’ll try to flip the heater wires around, but I doubt that will solve much. I’m going to need to check for 12v on both sides of the heater and go from there.
I switched both the white wires around, same thing happening. I also tried switching the black and grey for ****s and giggles, same thing happens. I did unhook the primary oxygen sensor and the ODBII software was reading a constant .475. With the oxygen sensor plugged in, I was getting ups and downs betweek 0-.475. I tried both the old ECU and new one and same problem persists. I’m leaning towards a bad connector plug on the harness side. There is some slight damage, meaning the plug slides in to easy and the clip will not hold the molex plug from the oxygen sensor firmly. Thoughts?
well if the computer see’s the o2 is swinging, thats a good thing. That means the o2 is working and giving the computer a signal. Weither its a good signal, well i guess that takes more diag.
What you want to look at is short and long term fuel trim %'s. See if the computer is trying to add or subract fuel b/c of it. Assuming the o2’s are fine, then there might be another problem… but considering the codes you have, its not likely.
I would work on figureing out the heater first… its easier, so why not. If you have the correct resistance in the o2 sensor, then the only other place a fault would be is in the wiring. ECU would be the last thing to go bad. I dont know what the spec is on the wires going to the ecu, so if you find that, check it… in the mean time you can check resistance from the o2 to the ecu to make sure the wiring is a-ok. WORST case, you can trick the ecu with a resistor that is the same as what the element is supposed to be… im guessing at least 5w. You can even put it right at the ecu to eliminate the possibility of the wiring out to the o2 being bad.
Do you have a FSM for the car? That would help!
The voltage for the oxygen sensor is swinging, but not enough to make me happy. I can’t even get short and long term fuel trims, because after a minute or two, the voltage will just drop off. I checked the resistance from the ECU to the wiring, everything appeared to be ok. I’m thinking it may be the molex connector on the ECU side that maybe giving me the issue. It looks slightly damaged, I’m going to go to the junkyard tomorrow to pick up a new one to wire it in. I have no clue what FSM is.
well any shady connectors can easily be figured out by checking resistance on each side of it. That should tell you if your making the connection.
FSM = Factory Service Manual