Some thoughts about oxygen sensors in 2.8L
#1
12-06-2008, 07:56 PM
Some thoughts about oxygen sensors in 2.8L
Hey everybody,
Just thought I would share some interesting insights about my recent work: O2 sensors. It started with the fault codes (reset them more than once and always came back) and the fact that I have to test emissions in 2 weeks:
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-10 - - - Intermittent
16805 - Warm Up Catalyst: Bank 1: Efficiency Below Threshold
I went somewhat paranoid after the catalyst code came up and immediately had nightmares about torchs, PB blaster and exhaust bolts.
Interestingly enough, I noticed *no change* in performance or gas mileage, despite the fact that the pre-cat O2 sensor was shot, as it usually happens.
Started by doing the pre-cat O2 and the sensor was definitely shot, all pitch black and zero response in the propane torch/multimeter test. Also, the car had no change in performance after the change.
Cleared codes and then vagged 1 week afterwards. Check engine light came up, vagged and then got codes for post cat sensor B1S2 (open circuit, resistance too high, bla bla). Funny enough no catalyst code and the B1S2 codes were not there before replacing B1S1.
Did the post-cat sensor (used one of those bosch universal - **** that was tough to get all the wiring done under the car and everything is hard to reach). Cleared codes, a few days have gone by and still no fault codes. Car runs like it always does, but no surprise there since the post-cat sensor is not as important as pre-cat.
Some I took some conclusions from this:
I drove without B1S1 for more than 5000 miles (and this after I got the codes for B1S1 and catalyst efficiency) and always the car seemed fine. My guess is the ECU was using only the measurement of sensor B2S1 for the air/gas mix and still performing appropriately. This would have prevented catalyst 1 from going bad, despite the code, since B1S2 was still working fine and regulating the mix for the engine which then goes to BOTH catalysts.
Bottom line: If you drive a 2.8 and got a bad pre-cat sensor, the respective catalyst might not be bad also if the other pre-cat is still doing fine. And post-cat codes might not show up if the pre-cat sensor is bad as well.
If this information is redundant, then sorry for the thread. Otherwise I think it's a good read for anybody with a 2.8L.
Take care.
Just thought I would share some interesting insights about my recent work: O2 sensors. It started with the fault codes (reset them more than once and always came back) and the fact that I have to test emissions in 2 weeks:
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-10 - - - Intermittent
16805 - Warm Up Catalyst: Bank 1: Efficiency Below Threshold
I went somewhat paranoid after the catalyst code came up and immediately had nightmares about torchs, PB blaster and exhaust bolts.
Interestingly enough, I noticed *no change* in performance or gas mileage, despite the fact that the pre-cat O2 sensor was shot, as it usually happens.
Started by doing the pre-cat O2 and the sensor was definitely shot, all pitch black and zero response in the propane torch/multimeter test. Also, the car had no change in performance after the change.
Cleared codes and then vagged 1 week afterwards. Check engine light came up, vagged and then got codes for post cat sensor B1S2 (open circuit, resistance too high, bla bla). Funny enough no catalyst code and the B1S2 codes were not there before replacing B1S1.
Did the post-cat sensor (used one of those bosch universal - **** that was tough to get all the wiring done under the car and everything is hard to reach). Cleared codes, a few days have gone by and still no fault codes. Car runs like it always does, but no surprise there since the post-cat sensor is not as important as pre-cat.
Some I took some conclusions from this:
I drove without B1S1 for more than 5000 miles (and this after I got the codes for B1S1 and catalyst efficiency) and always the car seemed fine. My guess is the ECU was using only the measurement of sensor B2S1 for the air/gas mix and still performing appropriately. This would have prevented catalyst 1 from going bad, despite the code, since B1S2 was still working fine and regulating the mix for the engine which then goes to BOTH catalysts.
Bottom line: If you drive a 2.8 and got a bad pre-cat sensor, the respective catalyst might not be bad also if the other pre-cat is still doing fine. And post-cat codes might not show up if the pre-cat sensor is bad as well.
If this information is redundant, then sorry for the thread. Otherwise I think it's a good read for anybody with a 2.8L.
Take care.
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