I suppose it could be the FET, IGBT or whatever the driver is. If we could only get the OP to make sense of his measurements at the connector. And what kind of chicken meter doesn't do dc current?
Code 21 Main oxygen sensor signal fault
- Thread starter noshine
- Start date
im also experiencing this exact problem after i did my rebuild....crazy thing about this is that before the rebuild the car ran perfectly fine...i mean no check engine no misfiring... its runs now but with a code 21 did a O2 change but the code still remains up
i have been trying to sort this code out as well... i was wonderin if u figured it out yet??? please keep us updated i to need to sort this code out...
ive taken off my whole harness to check all the wires and they all checked out good but the one thing i havent done is changing out the ecu
ive taken off my whole harness to check all the wires and they all checked out good but the one thing i havent done is changing out the ecu
found out what was the reason why my supra was spittin out code 21....i did a test to see if the o2 was getting any power at the ecu and sure enough it was so it boiled down to the o2 heat wire. i rechecked and traced it as far as a foot from where the o2 plugs into and found that my wire was cracked.. i thought it wasnt enough to prob loose any connection. i pulled it apart where the cracked wire had started to get kinda corroded and just like that the wire tore apart easily. i reconnected and code 21 gone atleast for right now.. test drove it for a good 20-30miles and no engine light so far everything seems fine idles perfect but starting to get a slight slower response to he throttle so might have to check the tps and prob timing now...
noshine;1942252 said:
Note: The ECU will only turn on the O2 sensors heater when the following parameters are met.
* When intake air flow is below a given point.
And
*Coolant temp is above 32°F
*specified time has elapsed after starting.(I am unsure what this time is. Pi or JJ might know.)
Until the parameters above are met you will read 12v to ground on both black lines. What you are seeing is 12v on the +B and the remaining voltage drop on the HT line. Since the ECU is waiting for the parameters to be met before grounding the HT line. And there should not be voltage between the two wires during this time, as your measurements indicate.
noshine;1942252 said:
As stated above, certain parameters need to be met before the ECU grounds the HT pin. Have you satisfied these parameters before testing?
True, it has the least authority, but open loop defaults to around a lambda of .9 and since best power mixture is richer than stoich he'll gain a bit going in that direction. Fuel economy will suffer as will catalyst efficiency though, since the lambda sensor is the most important emissions device on the engine.