Error code P0171

[Hanz Mannly]

Had this DTC pop up recently. So, I looked it up on the net and found that it has to do with the air/fuel mixture. Main cause of this is the MAF or air leak down stream from the MAF.

My question is - how can you test the MAF out of the vehicle to see if its good or not. just so I can rule that out.

Also, could it also be one of the O2 sensors ?

Thanks.

 

[Uncle Meat]

What year car is this on? I thought a P0171 was System Too Lean, Bank No. 1? If so it's more than likely an O2 sensor problem.

U.M.

 

[Hanz Mannly]

Yeah, I forgot to put the year in sorry. It is a 99 cobra.

And I suppose I should give a bit o' history on this.

I bought the car last year from a dealer (dealer will remain nameless to protect the innocent) (Pfft, ya right!). I had the vehicle inspected before I bought it. results showed that the CATs were taken off and (I believe) different O2 sensors installed to trick the system into thinking the CATs were still on. To be sure... I am not. They very well could be stock O2 sensors.

Whoever owned the car before me did a bad home weld job on the exhaust.

This raises another question with the no CATs on the car. Ive heard of good and bad things about having the CATS on and off. Just curious, how much would it effect the performance of the car to have them off ? The place I took it to said that when they test drove it, it didn't feel like a cobra normally does at the low end. And by putting CATs back on the car should fix the issue.

I have cleaned off the MAF to see if that was the issue. But, a couple of days later, the code popped up again.

Ideas ?

 

[Uncle Meat]

Sounds like one of the MIL's that were installed to "Fool" the O2 sensors once the cats were removed may be bad.

Not having the cats on the car can improve performance some.

U.M.

 

[Hanz Mannly]

Any way of testing them to find out which one is bad ?

If I keep those sensors and put cats back on... I would have to get all new sensors to get the system back to normal, correct ?

 

[Uncle Meat]

Well if the code is System Too Lean, Bank No. 1, bank #1 corresponds with the same side of the engine as cylinder #1, which on our motor is the passenger side. The real question here is whether it's the upstream O2 or the downstream O2 with the MIL, if it even has one. I don't know how to test an O2 sensor, sorry.

U.M.

 

[Hanz Mannly]

Thanks for the help U.M.

 

[Tupaukx]

I have an 04 cobra that had a bad MIL. It was throwing a code of P2270 and P2272. I bit the built and replaced both MIL's and 02 extension harness. NO more check engine light when the AC is turned on. CJPony Parts has the best prices and free shipping on Wednesday.