Micra Kangarooing - possible O2 sensor failure?

[Marie85]

Hi all, hoping you can help

I bought my 56 reg 1.2 Micra 2 years ago (Jan 2011) with about 25,000 miles on the clock. A few weeks after I got it, it started kangarooing (bumping up and down), losing power (not cutting out though) and surging forwards. I took it back to the garage under the warranty and they replaced an O2 sensor. The problem persisted, so they sent it to Nissan who replaced the OTHER sensor. All was well until this week (2 years on) ... I'm having the exact same problem again. The car is jumping, surging and losing power but not actually cutting out. Took it to a reliable local garage and the guy says he doesn't know if it's the O2 sensors (again) or the timing chain and wants me to get a diagnostic from Nissan which would cost £60. There's no rattle at all and the car has never actually cut out so I'm tempted to just go with the O2 sensors change anyway as it will cost about £140 in total. What do you think? The car is still under 40,000 miles (about 38,000 I think) so is it likely to be the timing chain?

Thank you in advance

 

[Marie85]

UPDATE: went with my gut feeling and had the O2 (lambda) sensors replaced without getting a diagnostic from Nissan. Went to my usual local garage and it cost about £200 and has sorted the problem. I think the same thing will most likely happen again at some point as it's not the first time the sensors have been replaced. Hope this helps anyone having similar problems.