Love seafoam, but now we have codes (1 Viewer)

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Hey guys. Did my annual seafoam treatment when I changed the oil this past Sunday. Nothing out of the ordinary occured. Certainlly had alot of smoke like usual. Everything was routine and the engine seemed to run better than before.

Last night, the check engine light came on. LX is running just fine so wasnt too concerned. Assumed it was the O2 sensor. Had it scanned this afternoon and got the following codes.

P0155- O2 sensor as expected.
C1340 - center diferential lock circut

WTF would cause the C1340 code?

Can the O2 sensor be cleaned or is it just an automatic replacement?

Thanks guys
 
Sea Foam has been known to kill o2 sensers. The other code may just be a fluke...like Bardiya says clear codes and recheck.
 
Let me clearify.....running sea foam through as a clean out through vacuum hose and letting it soak can load the senser with junk causing failure. Just adding sea foam to oil or gas normally causes no un wanted issues.
 
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Well cleared the codes, but the check engine light came back on after about 30 min of driving. Still pulling the same two codes, P0155- O2 sensor and C1340 - center diferential lock circuit.


According to another thread the PO155 is a O2 Sensor Heater Circuit Malfunction (Bank #2 Sensor #1).


Does anyone know if that is referring to the upstream sensor or the downstream sensor? Or does it make more sense to just replace both while I am in there anyways? Currently at 190K and I plan on keeping her for at least another 100K+, so I am all for replacing OEM parts with new OEM parts if it helps.


Now the C1340 code I have no idea what that is about. I have actually never ever engaged my center diff because its never been necessary. Anyone have any ideas on what would cause this. I am assuming the timing of this code is coincidental because I don't know how in the hell this would be related to using seafoam.


Let me clearify.....running sea foam through as a clean out through vacuum hose and letting it soak can load the senser with junk causing failure. Just adding sea foam to oil or gas normally causes no un wanted issues.

Going to date myself here, but I have been using seafoam for around 25 years now and have used it in everything I have owned. I actually use it in gas, oil, and via a vacuum hose. Typically do the vacuum treatment once a year. To be honest, I am way over do for a O2 sensor to go out. In all the years I have used it I have never had one go out and I always assume it was bound to happen. Especially at 190K as I am sure they were not in the best of shape anyways.
 
Here is robred's great site on O2 sensors that will tell you which ones go where. Replace the sensor(s), then clear the codes and see if the CDL code comes back. It may not, but if you've never engaged it, it's possible that's throwing its own code incidental to the O2 code.

Oxygen Sensor (O2) Part Numbers and Replacement
 
If it's the downstream sensor (I might be forgetting this) it's no biggie. Mine have been throwing codes for years. Doesn't affect anything. There's a chance I have it backwards and the upstream sensor is the one that doesn't matter.
 
If it's the downstream sensor (I might be forgetting this) it's no biggie. Mine have been throwing codes for years. Doesn't affect anything. There's a chance I have it backwards and the upstream sensor is the one that doesn't matter.
IIRC, you're correct - the upstream sensor helps the ECU determine fuel trims, the downstream sensor essentially tells you if the cats are working properly.
 

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