Question98 mustang v-6 3.8 litre 5-speed w/ac 129,000 miles
check engine light is on.
codes are:
p-171 to lean bank 1
p-174 to lean bank 2
p 1131 lack of 02 switching (I may not have this description exactly right)
p-1150
p-1151
I believe the last 2 codes are 02 sensor related.
The car seems to run ok but it is loosing some coolant and I can find no external leaks. Could this be related if there is an internal leak to the intake runners? I will try to get a pressure tester tomorrow. There is no coolant in the oil.
There are 4 02 sensors and I find it hard to believe they are all bad.
If I make a repair how do I clear the codes and turn off the check engine light?
Thanks for your help.
AnswerP0171 (bank 1) & P0174 (bank 2) fuel/air ratio is too LEAN.
The fuel trim system is at the rich correction limit.
P1131 (bank 1)& P1151 (bank 2) fuel/air ratio is correcting rich for an overly LEAN condition.
P1150 - indicate the fuel control system has reached maximum compensation for a LEAN or rich condition and the HO2S is not switching.
All of these DTC's point to a lean condition.
For starters:
A Vacuum leak in the Air Intake System.
A leak in the EVAP System.
A bad MAF sensor.
A stuck or leaking EGR Valve.
I don't think that the loss of coolant is causing these codes, but it should be repaired.
I don't believe all four Oxygen Sensors are bad. If one is not switching and that code returns after you make the repair, it is most likely bad.
The codes can be cleared by disconnecting the battery for about 10 minutes, and the Check Engine Light will go off. The codes and Check Engine Light will return if the condition is still there.
I hope this helps,
Dave
