My Malfunction Indicator (Engine Check) light just came on.
Coincidentally I also just had my car inspected and
emissions checks were ok. I have 80k miles on the car
and this happened at 20k and more recently at 74K
(8 months ago). The dealer indicated the 02 sensor failed again and charged me $235 to replace. Before I pay this again:

1. Is this a known faulty part?
2. Shouldn't they last more than 6K miles and do I have grounds to press the dealer on this?
2. Could it be something else this time?
3. Is this anything I could do myself ?

Don

 

http://vbxmaxima.8m.com/ecu.html .
Check out the code, come back with it, and someone can help you further. As for your other questions, the O2 sensor failure is common on Maximas. The MIL(check engine light comes on for numerous reasons, not all directly related to the emmisions system, from a loose gas cap to a cylinder misfire.

 

Your Maxima has three Oxygen Sensors. Are you sure the one which has just gone bad is the same one which was replaced 8 months ago? The rest of this post assumes that the answer is "yes".

1) No. There were some faulty original equipment Oxygen Sensors on '95 Maximas which were replaced as warranty repairs. This would not apply to a sensor installed on your car 8 months ago.

2) Yes. Bosch recommends replacing heated Oxygen Sensors such as used on the 4Gen Maxima after 100K miles. See http://www.volksparts.com/o2sensors.htm

3) Yes.

Maybe the sensor is bad because it was "poisoned" by exposure to a substance such as anti-freeze, anti-seize, RTV sealants, or the residue of burned engine oil.

Maybe an engine problem is causing an over-rich mixture. This could be the result of
- a bad Engine Coolant Temperature Sensor
- a bad Fuel Pressure Regulator
- an obstructed fuel return line
- sticking fuel injectors
- a clogged air filter

A failed Oxygen Sensor may be delivering a message about a problem elsewhere in the engine. The sensor may be an innocent victim in this crime story. I suspect that, 8K miles ago, the dealer failed to look beyond the immediate problem and identify the root cause. He installed a new Oxygen Sensor which failed for the same reason. If you put in a replacement today it too may fail in 8K miles or even sooner.

4) Yes. The part costs about $80. You will need a good floor jack, a pair of sturdy jackstands, and an assortment of hand tools. See the Chilton repair manual (page 4-14) or the Haynes repair manual (page 6-15).


I've read that a bad Oxygen Sensor can sometimes be rejuvenated by removing it, clamping it in a vise, and heating the sensing tip red hot with a propane torch. This is said to burn off a crust of deposits which interfere with its operation. I've never tried this torch trick myself, so cannot vouch for it's effectiveness. If you have a sensor which is already dead, you have little to lose.