rich4368

My 2010 GL350 now 47.5k and 4.5 years old, just out of warranty. CEL came on a week ago brought it in to dealer today was told faulty oxygen sensor. Took them over an hour to diagnose the problem was told because they have to check all 4 sensors. $450 for the part and $200 for labor. Was it because Diesel the O2 sensor so expensive? O2 sensor lasts over 10 years on my other cars just don't know if it is normal to have it faulty so early on GL350. I was still getting 27-28 mpg on highway since CEL came on but lack of power from stop. Anyway will pick up the car tomorrow and see if it runs better.

2010GL550

Just curious if everything is working properly for you. Ours is a 2010 GL550 but we had some strange oxygen sensor issues over the last twelve months. First fault/sensor was replaced under warranty about a year ago. In November we had another fault and paid $750 (out of warranty now) to have it replaced. In December got the fault again and was told the same thing. I escalated to Service Manager. They said it might be "bad gas". A day later the vehicle was ready and NO CHARGE. I suspect it was a wiring issue that was never detected/diagnosed in the first place! Anyway almost five months and no troubles. Good luck!

rich4368

The O2 sensor replacement costs $769 and was done by the same dealer that I have been going to for 7 years. Pickup the GL and drove about 500 miles. CEL never came back but I noticed a slight drop of about 1 mpg. The slight drop of mpg might have been they readjusted my tires pressure since I had them set 2psi higher for each tire before went in to the shop.

N_Jay

The drop in MPG can also be due to the system relearning.