C6 Oxygen Sensor - Help & Advice

[Jayhan12]

Please could someone advise me on best way to sort issue.

I have scanned the EML to flag code for Bank 2 Sensor 1 oxygen sensor so (passenger side before cats)

Now my car does not have any cats and only the 2 sensors visible at the end of the headers into mid section.

Would this be referring to these or is it the case that the previous sensors were coded out and there is another issue?

Should I replace the 2 the car has and this should don't he trick??

Best, J

 

[teamzr1]

You need to give more detail and answer these ?

1. how many miles on the engine ?
2. how old are the O2 sensors ?
3. were the rear (s2s) O2 sensors removed and via the PCM tune turn off the errors codes for them ?
4. what exactly is the problem engine is having ?
5. Do you own a OBD2 scanner to monitor engine functions like O2 sensors, fuel trims, timing, engine knock ?
6. exactly is the DTC number ?
7. check for any air or exhaust leaks ?
8. Last time the fuel injectors were cleaned ?
9. Same for the MAF and throttlebody ?
10. how long since the exhaust mods were done ?

 

[Jayhan12]

So this is the fault.
Works were done before my ownership
76k mileage
TexasSpeed Long Tube Headers
X pipe
Only 2 sensors in the system at bottom of headers where they connect to centre exhaust section.

 

[teamzr1]

When you used this Launch scanner was the engine running or not ?
Top left corner shows voltage low at 11.5 volts and needs corrected

I would look at the S2B1 O2 sensor wiring closely
It has 4 wires, use a multimeter and check each for as below

1. ground
2. 12 volts from heater fuse
3. PCM sends 0.450 mVolts to the O2 sensor
4. O2 sensor output, send the reading to the PCM for it to react to

These are long tube headers and because of that the O2 sensors are located further downstream
This means the wiring of the O2 sensors are now too short
Vendors suck customers in saying that do not need the rear S2 O2s, this is to con customers to take rear O2s
being their wiring is longer and place them in the S1s (upstream)

BUT, those wires are too long so they have people bundle up the excess wiring and like tie-wrap them
That is bad as there is a airchanel between the wire and the insulation, it is needed as the O2s require
outside colder air reference, hence they crimped off the airchannel
Also, if done wrong the wires are needed the exhaust and melt shorting out the O2 and could either blow the heater fuse
or worse short out the O2s electronics of the PCM

Or they cut the wires to shorten them, but that destroys the air channel

1. Check the header fuse
2. check the O2 wiring for cuts, broken or melted
3. check the O2 wiring connector to the wiring connector of the main wireloom from the PCM being pins are clean and not melted

Also look for the DTCs that tripped that the exhaust valves further back, either was not installed or wiring issues

Best case is those rear S2 O2s should be put back in mounted further back, normally after the CATs
as PCM uses those to determine average fuel injector ON time for non WOT engine conditions

Note : O2 sensors cannot be "coded out"
All that can be done is via the tune is turning off or degrade the DTCs for them as not trip those codes but the PCM is still reacting to no voltage readings from the S2s

Also, not having anything plugged into the S2 O2 wiring connectors from the PCM is like an antenna to those wiring pins and have negative effect to the PCM

 

[Custom exotics]

Need to know how the cats have been removed ie new long tube headers or just cut out and welded look to see if there are 2 more sensors closer to the engine end these will be the pre cat sensors you might find the post cat sensors still in situ but have been programmed out .

 

[Jayhan12]

When you used this Launch scanner was the engine running or not ?
Top left corner shows voltage low at 11.5 volts and needs corrected

I would look at the S2B1 O2 sensor wiring closely
It has 4 wires, use a multimeter and check each for as below

1. ground
2. 12 volts from heater fuse
3. PCM sends 0.450 mVolts to the O2 sensor
4. O2 sensor output, send the reading to the PCM for it to react to

These are long tube headers and because of that the O2 sensors are located further downstream
This means the wiring of the O2 sensors are now too short
Vendors suck customers in saying that do not need the rear S2 O2s, this is to con customers to take rear O2s
being their wiring is longer and place them in the S1s (upstream)

BUT, those wires are too long so they have people bundle up the excess wiring and like tie-wrap them
That is bad as there is a airchanel between the wire and the insulation, it is needed as the O2s require
outside colder air reference, hence they crimped off the airchannel
Also, if done wrong the wires are needed the exhaust and melt shorting out the O2 and could either blow the heater fuse
or worse short out the O2s electronics of the PCM

Or they cut the wires to shorten them, but that destroys the air channel

1. Check the header fuse
2. check the O2 wiring for cuts, broken or melted
3. check the O2 wiring connector to the wiring connector of the main wireloom from the PCM being pins are clean and not melted

Also look for the DTCs that tripped that the exhaust valves further back, either was not installed or wiring issues

Best case is those rear S2 O2s should be put back in mounted further back, normally after the CATs
as PCM uses those to determine average fuel injector ON time for non WOT engine conditions

Awesome. Really appreciate all the detail and will do as advised. Many thanks

 

[Jayhan12]

Need to know how the cats have been removed ie new long tube headers or just cut out and welded look to see if there are 2 more sensors closer to the engine end these will be the pre cat sensors you might find the post cat sensors still in situ but have been programmed out .

No there are definitely only 2 further "downstream" I'm certain. Visually from inspecting through the engine bay and below. TexasSpeed straight into centre section.

 

[teamzr1]

Example of the custom exhaust I made for my 1999 C5 is a X-pipe in place of the CATs and the rear O2s installed along with the front S1s of the long tube headers