My Check engine light is on on my 2002 Discovery SE.

I have 4 codes coming up. I'm looking for suggestions on what to look at/for.

P0130-O2 Sensor Circuit malfunction Bank 1 Sensor 1

P0171-System too lean

P1171-Manufacturer control Fuel Air Metering

P1668-Manufacturer control Aux inputs and outputs

Brian in Austin[/align]

 

You probably need a new oxygen sensor. All 4 sensorswould need to be replaced at the same time. How many miles do you have on the truck, they tend to go bad around 100k miles. It could be your MAF sensor too, what type of air filter are you using?

 

Has 78 K on it. I Just bought it, trying to get it inspected. Im guessing stock paper air filter as the previous owner had an indy shop do the 60 K service.

Why do all four ($300??) O2 sensors need to be replaced??

 

Any way to test the MAF?

Brian

 

I don't know any way to test the MAF other than swapping in a good one. If the MAF is bad, you usually get other codes as well though. Just check to make sure that you have a paper filter and not a K&N, the sensors seem to be very sensitive to K&N filters.

People seem to have trouble only replacing one O2 sensor because they work together as a unit. There are ways to test them as far as resistance and voltage output, I would start off by making sure that the wiring and plug connections are all good first.

 

All four O2's need to be replaced at the same time because they go bad at the same time. And one or two good ones and the rest bad will set the ECU into a tail spin. It wont know what the hell is going on.
No there is no way to test the MAF, but for DII's they are cheap, $150.
Did the indy shop do a tune up on the truck? Did they replace the plug wires? If you can as the PO what was done during the 60K service.

 

thanks, I'll check wiring today. Any thoughts on where I can find out how to test the O2 Sensors for resistance etc?

Brian

 

Noway to test O2's.

 

without the right equip. you cant test most things on the car... you can check the heater circuit on the o2s, but that wont help you here. do you have an exhaust leak, itll be making noise on a cold start?

 

You should get very small voltage fluctuations from the sensorwhen you test it in the car, but I haven't done it before, I'm sure there are places to look it up. You can testfor continuityin the heater circuit and if it reads infinity it's shot,but many people say not to do this because it could hurt the sensor by sending a low voltage through it.They can be cleaned as well which might help. Your mileage seems a little low, but if you plan on keeping the car I would just replace them, but that's me. You might check for vacuum leaks to, that's cheap and easy and it could throw the lean codes at least.