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I've just swapped out (for the third time) my bank 2 sensor 1 HOS. I know for a fact in a few months it will fail again for the same reason. It keeps failing for the heater control circuit.
I suspected it was a wiring/loom issue but I have switched the sensors over and immediately replicated the fault on bank 1.
What would keep causing the same o2 sensor to fail for such a strange fault?
Sensors can not be touched or washed so why they come with a protective cover and when anti seize is applied to the threads it should not contact sensor area hope this helps.
What mod's, since if the heater in the O2 is burning out over and over again, then that bank is running way to rich at start up (or some other problem leading to the same), and the reason that the heater is left on way too long after initial start up instead.
What mod's, since if the heater in the O2 is burning out over and over again, then that bank is running way to rich at start up (or some other problem leading to the same), and the reason that the heater is left on way too long after initial start up instead.
I think you could be onto something here Dano.
The car has CAI, FAST, Headers, 160 Stat and a tune. All of this was done before I purchased it in 2011 with 60k miles.
I ran it daily in the USA for 5 years without any problems and put another 50k miles on her. Just before I moved back to UK the B2S1 HOS failed for the heater circuit and I swapped it out thinking 'oh well, 100k miles or so ain't bad!'
About 9 months later I got the CEL again and on reading the codes it was the same fault - new sensor remember. I had another new sensor so I thought 'OK, bad sensor maybe' but I was starting to also think maybe a loom issue. I also swapped out the sensor extension pigtails for new high quality racetronix ones as these looked a little tired.
Another year and 3 months has passed and boom, same codes. So yesterday I switched sensors between left and right and on second start up boom - same failure but has moved from B2S1 to B1S1 - as expected so it's deffo the sensor in my mind.
Another point of interest is that the car does smell really rich when cold but doesn't run rich when hot - we have a gas analysis every year for our equivalent of the smog test. It stinks very fuelly when cold.
Also, the sensor that had failed was quite a bit darker than the good one. Not horrendously sooty but blackened more than the other.
If the sensor is considerably darker than the other, especially if it's black, that is an indication of unburned fuel. Start checking injectors, fueling, etc on that side. Of course, thinking out loud, the sensor could be darker because the heater is not working properly.
The car has CAI, FAST, Headers, 160 Stat and a tune. All of this was done before I purchased it in 2011 with 60k miles.
I suspect your problem is in the area I highlighted.
Most tuners think the only thing you have to do to "tune" for a 160° thermostat is change the fan temps. I'd say 9 out of 10 that I've seen that were "tuned for a 160° thermostat" had no changes to the fuel mapping. If it's still mapped to try to warm up the engine to reach a stock thermostat, it's going to run rich, and that will burn up O2 sensors, catalysts, and cause other issues. It often makes underhood temps worse in traffic because of the extra heat from the catalyst trying to burn all the unburnt fuel in the exhaust.
Try a 180° thermostat, or take it to someone who knows how to tune the fuel maps to match a 160° thermostat.
Last edited by C6_Racer_X; Mar 16, 2018 at 08:28 AM.
I suspect your problem is in the area I highlighted.
Most tuners think the only thing you have to do to "tune" for a 160° thermostat is change the fan temps. I'd say 9 out of 10 that I've seen that were "tuned for a 160° thermostat" had no changes to the fuel mapping. If it's still mapped to try to warm up the engine to reach a stock thermostat, it's going to run rich, and that will burn up O2 sensors, catalysts, and cause other issues. It often makes underhood temps worse in traffic because of the extra heat from the catalyst trying to burn all the unburnt fuel in the exhaust.
Try a 180° thermostat, or take it to someone who knows how to tune the fuel maps to match a 160° thermostat.
A 180 t-stat is certainly not a bad idea, but he drove the car over 50k miles with no issues with a 160 t-stat.
I have been considering changing for a warmer 'stat' for sometime as I don't think there is any point me running as is. Like you say though BadAV, the car ran faultlessly for 50k miles and about 16 full days at SMMR so I was of the opinion 'if it ain't broke - don't fix it'.
Whatever has happened 2 years ago or so is causing the car to run rich on that bank (at least during warm up), i'm fairly certain of it now. Next job is to pull the plugs and see what they are saying. I will post pictures for your opinions gents which are greatly appreciated.
In the meantime, what causes the heater circuit to trip off? Is it coolant temp, the PCM seeing the sensor switching?, a period of time or a combination of these?
I am thinking it could be time to replace a few bits and get it tuned over here...
Plugs were about 40k miles ago, wires I have never changed but are MSD type and I assume done at same time as previous owner mods.
The car has CAI, FAST, Headers, 160 Stat and a tune. All of this was done before I purchased it in 2011 with 60k miles.
I ran it daily in the USA for 5 years without any problems and put another 50k miles on her. Just before I moved back to UK the B2S1 HOS failed for the heater circuit and I swapped it out thinking 'oh well, 100k miles or so ain't bad!'
About 9 months later I got the CEL again and on reading the codes it was the same fault - new sensor remember. I had another new sensor so I thought 'OK, bad sensor maybe' but I was starting to also think maybe a loom issue. I also swapped out the sensor extension pigtails for new high quality racetronix ones as these looked a little tired.
Another year and 3 months has passed and boom, same codes. So yesterday I switched sensors between left and right and on second start up boom - same failure but has moved from B2S1 to B1S1 - as expected so it's deffo the sensor in my mind.
Another point of interest is that the car does smell really rich when cold but doesn't run rich when hot - we have a gas analysis every year for our equivalent of the smog test. It stinks very fuelly when cold.
Also, the sensor that had failed was quite a bit darker than the good one. Not horrendously sooty but blackened more than the other.
The 180 Stat you refer to, is that the stock item? I am ordering some parts to come over the pond but on rockauto all I can find is a 187 degree stat. Is this a, the one you advise/refer to and b, the stock item?
Cheers!
Plan is to whip the plugs out tomorrow as it's a day off at last!
Here are the plugs as of this morning. Best guess is approx 30-40k and maybe 8-10 road course days over maybe 4 years? I did swap them myself but I have a terrible memory for such things!
I'm no expert but there doesn't seem to be much wrong? Happy to take input.
Nonetheless, 180 stat and new plugs en route from rock auto.
Bank1
Bank2
1
3
5
7
2
4
6
8
Last edited by Legal Alien; Mar 22, 2018 at 10:37 AM.
Reason: image hosting faff
My main concern is this is a 'new' problem for me. The car behaved in it's current guise for years and something has changed. I don't think I can blame the headers for that but i'm open to suggestions!!!
It does make logical sense to me that the only thing that would burn the heater out is overuse. It's why it is staying on (on only one bank) that has me baffled.
last night i wrapped my headers up to the 02 sensors. to try to keep the heat in the pipes to make the 02s heaters not working so hard.
wasnt terribly hard. about an hour.
and no wonder the tunnel and floor boards get hot. the driverside header sits 1/4" away from the tunnel pretty much the whole way. barely enough room to get wrap threw. no room in some spots.
should be a cheap/easy test/fix i hope.
my new 02s come in today.
my pass side O2 was blacker than the drivers side.
the pass side is the one that always burns out. however this time both burned out for the first time.
Last edited by STANG KILLA SS; Mar 22, 2018 at 01:36 PM.
Keep blowing same O2 sensor???
