Replaced 02 upstream sensor and still codes
#1
Replaced 02 upstream sensor and still codes
Hey I own a Jaguar xk8 2001 coupe
I just replaced the toughest sensor I ever did I swear. And after putting in the new denso sensor it's still saying code 1646.
A little context, I took two days getting the old one off. I replaced sparkplugs while I had the intake off and after putting everything back and unplugging the sensor (it was cut off in the effort to replace it) the car idle was very rough and the brakes were hard and stiff like the brake booster wasn't even working proper. It gave codes such as low and high circuit to the O2 sensor (bank one upstream) because it was disconnected so I knew it was definitely what I was working on
Nonetheless, I continued and managed to get the new part in, plugged it up. Cleared codes and let the car sit with the battery disconnected for an hour. Afterwards I plugged it back up and started it. Still rough idle, like the car shakes idle. Drove it around up to temp, the brake were still hard and codes came back for 1646 the same code... Again. Could I have possibly tripped a relay/fuse? Is there one associated with it? Could this fuse also be in relation to the brake booster?
I just replaced the toughest sensor I ever did I swear. And after putting in the new denso sensor it's still saying code 1646.
A little context, I took two days getting the old one off. I replaced sparkplugs while I had the intake off and after putting everything back and unplugging the sensor (it was cut off in the effort to replace it) the car idle was very rough and the brakes were hard and stiff like the brake booster wasn't even working proper. It gave codes such as low and high circuit to the O2 sensor (bank one upstream) because it was disconnected so I knew it was definitely what I was working on
Nonetheless, I continued and managed to get the new part in, plugged it up. Cleared codes and let the car sit with the battery disconnected for an hour. Afterwards I plugged it back up and started it. Still rough idle, like the car shakes idle. Drove it around up to temp, the brake were still hard and codes came back for 1646 the same code... Again. Could I have possibly tripped a relay/fuse? Is there one associated with it? Could this fuse also be in relation to the brake booster?
#3
#4
As for the brake booster I'm still not sure. I'm going to check the fuses and see. I feel as if it may be a part of the damping module. And maybe the fuse blew giving low power to it. It's raining today so I'm waiting for things to calm down before accessing the issues once again
#5
#6
Yep, what did you do to remedy this? Or some possible things I should check to see why this is happening.
#7
I had a hard time replacing the O2 sensor, but did not touch anything else, and had no trouble codes or fault after that.
I always suspect the last thing that was done to a car when faults occurs.
To check for vacuum leaks you can use some starting fluid, brake cleaner or other highly flammable liquid and spray it around the intake, pipes and hoses that is connected while the engine idles. If there is a leak you will hear the engine respond. If that sounds scary, you can use a smoke machine to fill the intake system with smoke and see where it comes out.
I always suspect the last thing that was done to a car when faults occurs.
To check for vacuum leaks you can use some starting fluid, brake cleaner or other highly flammable liquid and spray it around the intake, pipes and hoses that is connected while the engine idles. If there is a leak you will hear the engine respond. If that sounds scary, you can use a smoke machine to fill the intake system with smoke and see where it comes out.
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#8
I had a hard time replacing the O2 sensor, but did not touch anything else, and had no trouble codes or fault after that.
I always suspect the last thing that was done to a car when faults occurs.
To check for vacuum leaks you can use some starting fluid, brake cleaner or other highly flammable liquid and spray it around the intake, pipes and hoses that is connected while the engine idles. If there is a leak you will hear the engine respond. If that sounds scary, you can use a smoke machine to fill the intake system with smoke and see where it comes out.
I always suspect the last thing that was done to a car when faults occurs.
To check for vacuum leaks you can use some starting fluid, brake cleaner or other highly flammable liquid and spray it around the intake, pipes and hoses that is connected while the engine idles. If there is a leak you will hear the engine respond. If that sounds scary, you can use a smoke machine to fill the intake system with smoke and see where it comes out.
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cjd777 (04-04-2024)
#10
Thanks, back to the issue of the 02 sensor, replaced it with a good part from RockAuto (denso) and it still creates a check engine light. Now today I used an OBD2 to monitor the live stream of the sensors. Only two sensors were reading correctly while the others said N/A.
Here are those sensors indicated by the general Livestream
O2b2s1
02b2s2
02b3s1
02b4s1
02b4s2
All N/A, I'm starting to wonder if this is a fuse or relay. The only code the ecm puts out is p1646. If It's wiring does anyone have a diagram of the output wire. And if relay.. what relay should I check for p1646.
Here are those sensors indicated by the general Livestream
O2b2s1
02b2s2
02b3s1
02b4s1
02b4s2
All N/A, I'm starting to wonder if this is a fuse or relay. The only code the ecm puts out is p1646. If It's wiring does anyone have a diagram of the output wire. And if relay.. what relay should I check for p1646.
Last edited by ocwolfy; 04-05-2024 at 01:19 PM.
#11
Here's an update from today, so I tested all the relays in the passenger side bulk head. All prove to be working. I checked the passenger side fuse box, everything there is not blown, I did not check the actual fuse box relay.
I tested the new 02 sensor to see if the heater element was working. And... It was. I checked the previous sensor, it worked too. Then I check the original OEM one from 20 years ago, it doesn't work.
To add, I unplugged the sensor while the car ran, no change, it powers it but is not acting on communication. I even tested the power from the harness to the 02, it works. Ruling out power failure, relay failure, fuse failure.
Checked the wire, from the harness into the fire wall there is no damage. And I still can't get live data in OBD2, unless I'm not supposed to see it. When checking readiness systems it also gives a fail as all monitoring systems "are not active".
Honestly I'm about to just give up and deal with the bad gas milage. The fact that the restoration on the car has included a fair amount of blown modules like the chair, slm and abs makes me fear the engine control module isn't so clean either.
Any thoughts?
I tested the new 02 sensor to see if the heater element was working. And... It was. I checked the previous sensor, it worked too. Then I check the original OEM one from 20 years ago, it doesn't work.
To add, I unplugged the sensor while the car ran, no change, it powers it but is not acting on communication. I even tested the power from the harness to the 02, it works. Ruling out power failure, relay failure, fuse failure.
Checked the wire, from the harness into the fire wall there is no damage. And I still can't get live data in OBD2, unless I'm not supposed to see it. When checking readiness systems it also gives a fail as all monitoring systems "are not active".
Honestly I'm about to just give up and deal with the bad gas milage. The fact that the restoration on the car has included a fair amount of blown modules like the chair, slm and abs makes me fear the engine control module isn't so clean either.
Any thoughts?
#12
#13
I'll try one of my different ones. We have a bunch. I just what was convenient (our garage is a mess). I'll reassess on Sunday with my 900$ tool for 2012 for 2010 and below. I'll update when I find the problem
#14
A little update on the issue, so I used my good scan tool after rearranging my garage and finding it. And found this within the diagnostics.
Following this I also bench tested the 02 sensors and they both work, the heating element and the they both are transmitting data within the correct the limits. Yet readiness system stay incomplete. Does anyone have any idea would I should do next. Because I'm guessing I should just rip the ecu out and check for shortages at this point.
Here are the pictures from diagnostics. Didn't include the code but its still p1646, and what's the possibility its the downstream sensor sharing the same code?
Following this I also bench tested the 02 sensors and they both work, the heating element and the they both are transmitting data within the correct the limits. Yet readiness system stay incomplete. Does anyone have any idea would I should do next. Because I'm guessing I should just rip the ecu out and check for shortages at this point.
Here are the pictures from diagnostics. Didn't include the code but its still p1646, and what's the possibility its the downstream sensor sharing the same code?
#15
P1646 refers to the upstream sensor on the RIGHT cataverter.(you are talking about the RH side of the engine?)
#16
Yes the one on the passenger side (right side) for the LHD model. I've replaced that sensor 3 times with a denso OEM part and when it still didn't work I bench tested it. It was working perfectly. Both the heating element and it's data stream (tested with a. Meter).
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motorcarman (04-30-2024)
#19
Best of luck, keep us posted.
#20
Hmm, I was not aware these upstream sensors could easily be tested. Just to be sure, have you checked the upstream sensors you are replacing a _wideband_ sensors, not lambda like the downstream? They work quite differently and are not interchangeable.
Best of luck, keep us posted.
Best of luck, keep us posted.
Yes, it's the wideband, because they are expensive. According to RockAuto it's the right part and it was 225$.