The check engine light went on yesterday although the car was running fine. I hooked up the OBD connection last night and found I had a P0137 which is low voltage from the second O2 sensor. I reset the ECU and it is gone and has not reoccurred in a short check ride.

Anyone else experience this?

The sensors have been out numerous times during transmission and clutch work so I am wondering if it could be damage to the sensor or wiring causing an intermittent short. Or is there something else to suspect? The troubleshooting flow moves on to a faulty ECU but does that make sense? How many of those go bad?

Just looking for similar experiences.

 

From what I've read, the secondary O2 may not generate a CEL until the ECU can see multiple driving cycles.

 

No similar experience, sorry.

What's the prognosis (in the manual) for a low O2 voltage? Low *sensed* voltage, meaning it thinks the reported O2 level is incorrect, or out of range?

If that's the case, I highly doubt it's wiring. More than likely wiring would result in an open connection or a short, so I doubt you would get that kind of a code.

My guess would be a dying O2... if it comes back, you might try swapping with another O2. I have a used one that I think might work if you need one to play with temporarily.

 

Thanks Todd. I have made a few short trips with no reoccurrence. I wonder if the sensor is covered under the emissions or extended warranty.

 

O2 sensors should be covered under the emissions warranty, so I'd give that a shot. The only cars I've seen with secondary O2 faults tend to be supercharged cars (for some reason). I've seen two heater circuit failures. The 2nd O2, since its after the cat (or in the middle of it) and further from the engine may have to work its heater harder, but that seems a sketchy explanation at best.

I'd just have the dealer handle it if possible.

UL

 

I've also been getting a recurring (after maybe half dozen start cycles) CEL after removing and reinstalling the stock airbox.

Checked the obvious, like MAP sensor, vacuum lines, gas cap, etc.

Looks like I might need a trip to the dealer to read the codes unless someone has a great idea...