Mustahg code help please


Old 09-18-04, 07:33 AM
Thread Starter
Join Date: Aug 2003
Posts: 478
Question Mustang code help please

!998 Mustang v-6 3.8 liter 5 speed air cond

Check engine light is on. It is showing codes:
P 171 Too lean bank 1
P 174 Too lean bank 2
P 1131 Lack of H02S1 switches lean bank 1 sensor 1
P 1150 Lack of H02S1 switches bank 2 sensor 1
P 1151 Lack of H02S1 switches lean bank 2 sensor 1

The car has 4 o2 sensors.

Also I don't know if it could be related but the car is loosing some coolant but can't find a leak. Could the coolant be entering the intake runners and have contaminated the 02 sensors?

My guess is the front oxygen (02) sensors are bad.

Help please. Also after repairs how do I clear the codes and get the check engine light off.


Last edited by car nut; 09-19-04 at 11:24 AM.
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Old 09-21-04, 09:07 AM
Join Date: Aug 2003
Location: Cape Cod
Posts: 4,320

I don't speak obd-II real well, but I do know that lack of a Heated O2 Sensor switching doesn't nessesarily mean the sensor is bad
Did you check the MAF sensor for crud?
I do know you'll need a scanner to reset the light
Old 09-21-04, 11:09 AM
Thread Starter
Join Date: Aug 2003
Posts: 478
Thanks for the reply slickshift. From what I have learned so far the problem could be egr valve which I believe I have eliminated, intake system leak but I find no leaks, evap system leaks again I find no leaks. I will check the maf for crud and I found a voltage test for the maf. As soon as I can get the car back I will check it out. A ford mechanic said if you un hook the battery for 10 minutes it will clear the codes & re set the light.
Old 09-21-04, 01:11 PM
Join Date: Dec 2001
Posts: 2,538
it sounds like the engine is just running lean whether it be from the maf, fuel pressure, or a vacum leak.
suggest you have the cooling system pressure test done on the vehicle and also have it checked for head gasket leaking by having a block check or gas anilizer test done on the cooling system by a shop.

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