2003 Land Rover Freelander Se 2.5 L V6 130,000 km

MIL came on, with these codes stored:

P1149 - Lambda regulation post cat bank 2 above rich delay time
P2099 - Post Catalyst fuel trim too rich Bank 2

I changed the upstream & downstream O2 sensors on Bank 2 (RH or most rearward bank?? transverse engine...)

The MIL came back on with the P1149 code only. Drove the vehicle with a graphing scantool monitoring all 4 O2 sensors... The upstream sensors both appeared normal with good crosscounts. BUT the downstream (post cat) sensors both are reading quite high voltage at times! LH rear sensor reaches 0.986V and RH reaches 0.990V which then sets code P1149 and illuminate the MIL.

It is my understanding that the post cat sensors should remain at a relatively low voltage reading, if all systems are working properly, including the Cats.......??

If the Cats were faulty (and not plugged) I'd assume the rear O2 sensors to mimick the fronts.....??

What would cause such a high O2 sensor reading from the rear sensors???

I am not very familiar with Land Rovers, but I figure the basic operating principles would be the same as anything else.

Has anybody here seen or heard of anything like this? Any advice? Ideas?


All replies will be appreciated!! Thanks

 

if the spark plugs are not pink from coolant then the catalytic converter is damaged.

seen it a few times on hack jobs that tried to weld the flex pipe.

 

Thanks Rovin4life. So, are you saying possible head gasket leakage? Is that common with these engines?

Will coolant in the exhaust cause a high O2 sensor voltage??

There is no smoke out the exhaust, no smell of coolant, and no drivability issues.

Also, regarding welding on the flex pipe... Are you suggesting an exhaust leak or something else?

Thanks again

 

could be nothing but it will cost nothing to check either: Inspect your mass airflow sensor for dirt. I got faulty O2 sensor codes too on a my 99 D2, but it turned out to be a badly clogged air flow sensor. Mechanic replaced, O2 codes gone.
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freelander is a completely different vehicle.

 

Hi I have recently purchased a freelander and when I start the car the fan comes on straight away when cold and shortly after that sometimes even a while the car seems to be getting to much petrol and stalls because of flooding you can smell it really bad once car stalls is this caused by the oxygen sensor or water temp sensor? or something else even? catalic converter?

 

Majic word there - "fan" - there are two fans, and controlled by a crafty dedicated ECU, all noted in attached page from the RAVE. But I noticed the last sentence - if one fan fails, the Fan ECU runs the other one at maximum speed. So check both.

Fan could be requested on by coolant temp sensor, the AC system, or a signal from the transmission. You may need to get codes read by dealer or sophisticated shop.

As for running rich, codes may show up for that as well. The engine coolant temp sensor could fool truck into sending more fuel, or it could be unplugged and truck thinks it is -40F outside and is compensating. Because it "believes" the sensor, may not be a code. A scanner can tell you if engine coolant temp sensor is producing an expected value.

 

Great cheers thanks for that I'll go and have a look right now and I'll let you know how i go