How do I fix Odyssey with faulty O2 sensor heater circuit
Hi, Scotty and all.
I've a problem - code P135 - faulty heater circuit of primary (upstream) O2 sensor (new).
car: 2002 Honda Odyssey w 250000 miles. New catalytic converter w/ Y-pipe and both O2 sensors (ultra Power). Van has 1 upstream and 1 downstream sensors.
Simptoms: running rich (exhaust smells "unburnt"), at best 20MPG, and error code. Can't pass emission inspection.
Previous owner bypassed old O2 sensor with one black wire (for heater element) connected to a fuse below dash board (drivers side). I removed all these extra wires...
New upstream O2 sensor has 6 Ohm resistance between black wires (heater element). It must be bet. 10 and 40 Ohms.
Initial diagnosis (by automechanic)- bad CMU, replaced ECU (with VIN re-programming) - problem persists.
I spliced one of the black wires and installed a resistor (10 Ohms) - total resistance was now about 16 Ohms.
I traced white and green wires from O2 sensor harness to the CMU.
I check continuity of harness black wire to the ground - good.
Still have code P0135.
I think that I need to purchase Denso upstream O2 sensor (part # 2344727). Maybe its resistance is within the specs.
What do you think? what would you suggest?
Thanks in advance...
Did you use the OEM oxygen sensor? The symptoms say that the sensor is not functioning correctly. I would replace the oxygen sensor.
The pre-heater in the 02 sensor isn't working. Get OEM part.
Read through here and perform the troubleshooting they suggest:
New primary (upstream) O2 sensor (Denso 234-4727) is installed to no avail. code P0135 still comes up.
I used a troubleshooting procedure, posted in 2013 OdyClub site and got to the point where there's a short between primary O2 heater wire #4 and fuse #6 (ECU/Cruise Control internal fusebox by driver side).
Troubleshooting guide can be found here: file:///home/silver-dell/Downloads/P0135(1).pdf
by the way, new O2 sensor has 6.xx Ohm resistance, not 10-40 Ohm per specs.
Also, I found how to diagnose MAP sensor (on top of Throttle body between rubber boot and intake).
Per specs, center pin must read 1.4-1.9V at 2500 rpms. Mine did not, it read 0.78V or so. Although the voltage at idle was fine (1.11V) (normal is 0.9-1.1V at idle).
Primary O2 wire at #4 (BLK to BLK/YEL) terminal goes to a junction called J/C C107 where another 3 BLK/YEL wires joint. This junction is located somewhere "below center of dash". I could not find this junction/connection, not wires anywhere in that area.
Could the be in wire bundle plugged into the ECU? or is it a separate junction?
any thoughts? experience?