PO171 OBD2 error code - mixture too lean

LpPepper

Hi all,

Engine check light came on and Obd reader says it's Po171 - mixture too lean. I cleared the code but it came back a few days later. Car is a 04 Micra 1.0L petrol. It seems to be using a bit more petrol than usual since the code came on, and as weird as it may sound there seems to be a fairly noticeable smell of petrol around the car when it's running - never noticed it since before now. Also when the engine is cold it seems a lot more hesitant for the first 5-10mins - put down the throttle in low revs and it definitely takes its time...

Brought to local garage and they changed spark plugs, there was about 13,000miles on them.

That was last week and now the engine check light came on again - i assume it's the same code.

Any ideas on what it could be? 02 sensor, air flow sensor, MAF?

Thanks

porsche boy

Realistically it could be a few things...
Is the airbox sitting properly on the throttle body? Perhaps bring it to a different garage???

redline2015

LpPepper wrote: »

Hi all,

Engine check light came on and Obd reader says it's Po171 - mixture too lean. I cleared the code but it came back a few days later. Car is a 04 Micra 1.0L petrol. It seems to be using a bit more petrol than usual since the code came on, and as weird as it may sound there seems to be a fairly noticeable smell of petrol around the car when it's running - never noticed it since before now. Also when the engine is cold it seems a lot more hesitant for the first 5-10mins - put down the throttle in low revs and it definitely takes its time...

Brought to local garage and they changed spark plugs, there was about 13,000miles on them.

That was last week and now the engine check light came on again - i assume it's the same code.

Any ideas on what it could be? 02 sensor, air flow sensor, MAF?

Thanks

Had the exact same symtems and code on my Nissan note ...
Cataclean sorted it for about a year...Then it came back on, replaced o2 sensor...Job done

I have an o2 sensor socket in tallaght if your stuck getting it out

gearoidol

have the same error with same higher than normal fuel consumption on a 06 golf gti ,so far my mechanic and main dealer has not managed to fix, changed maf,front o2 sensor and checked hoses of air intake ,comes back on after 200km ,really annoying me

LpPepper

I have just noticed a small hole in the exhaust pipe coming just under the engine bay i.e. just after manifold. There is a strong smell of fuel/exhaust fumes in the cabin especially when stopped in traffic which is fairly noticeable since the engine check light came on Along with rough performance, bad fuel economy and hesitation.

Could this small hole in the exhaust pipe be the culprit??

christy02

LpPepper wrote:

Engine check light came on and Obd reader says it's Po171 - mixture too lean. I cleared the code but it came back a few days later. Car is a 04 Micra 1.0L petrol. It seems to be using a bit more petrol than usual since the code came on, and as weird as it may sound there seems to be a fairly noticeable smell of petrol around the car when it's running - never noticed it since before now. Also when the engine is cold it seems a lot more hesitant for the first 5-10mins - put down the throttle in low revs and it definitely takes its time...

The cam position sensor causes similar symptoms and is prone to go on the k12 micra. If it is that it may be difficult to start as well as being lumpy until it warms up. Should throw up its own code though p0340.
Cheap enough part may be worth changing to see if that solves problem.

LpPepper

christy02 wrote: »

The cam position sensor causes similar symptoms and is prone to go on the k12 micra. If it is that it may be difficult to start as well as being lumpy until it warms up. Should throw up its own code though p0340.
Cheap enough part may be worth changing to see if that solves problem.

Timing chain was replaced around 10,000 miles ago, would can sensor really throw up a PO171 lean code ?

christy02

LpPepper wrote:

Timing chain was replaced around 10,000 miles ago, would can sensor really throw up a PO171 lean code ?

Wouldn't have thought so, but symptoms sound similar. Was camshaft sensor replaced at same time as chain?

LpPepper

christy02 wrote: »

Wouldn't have thought so, but symptoms sound similar. Was camshaft sensor replaced at same time as chain?

No just chain. That was about a year and a half ago. No rough running or similar symptoms since chain was replaced, until now

LpPepper

Just as an update - the 02 sensor was replaced and immediately the car went back to running as normal.