I have a 1997 528i (BMW), with 145,000 miles on it... the car started
running ruff at idle and the check engine light has come on. I am
getting 4 p-codes
p0170 fuel and air metering bank 1
p0173 fuel and air metering bank 2
p1188 linear 02 sensor compensator resistor short to B+
p1189 linear 02 sensor compensator resistor short to ground
Any Idea what has gone wrong and what I need to do to fix it?
It appears to me that these codes are related. There is a cascade effect
taking place, the codes are showing you the cascade.
I suggest you erase all codes and start the motor, then pull the codes
again. My guess is that the Major Code will be displayed by itself, and you
have one part to replace. You may have a problem with wires worn through,
but I doubt it. I suspect a failed part. If the P017n codes come up, look
for a cause that is common. If the P118n codes come up, my guess is the O2
sensor. Having said that, I've not experienced these codes before, and there
are other expected codes to pinpoint a defective O2 Sensor.
The fuel metering and the O2 sensors play together. That is, the fuel is
metered via the computer because of input the computer receives from the O2
sensor(s). The O2 sensors expect to be within a certain range, and if they
are outside of the range the computer alters the fuel metering to get the O2
sensor back into range. Odds favor one or the other system to be causing the
other system to be out of range. Both faults are reported, but only one
fault actually exists. This is why I suggest clearing all codes then
restarting the motor to see what comes up. The problem with the code list
you gave us is that one or the other came up early on in the problem set you
report, and we don't know how long it was stored before the other code set
came up. (Let's say it took you a few miles to realize the car was not happy
and you needed to park it. During that time, one set of codes came up but
the problem developed worse and the second problem came up. You do not know
what came first. Clearing the codes and starting the motor should give you
the worst (most significant) problem that exists.) The minor set of codes
could have come up long ago because some codes are stored but not reported
via the Check light.
On Oct 26, 7:49 am, firstname.lastname@example.org wrote:
Before changing any parts check the air intake boots for cracks/
splits, esp. by the throttle body, the little hose that branches off
for the idle valve always cracks. the neaxt thing is the crankcase
vent valve. with the car running remove the oilfill cap, lifting it up
slowly. there should be VERY SLIGHT vacuum resistance. if you pull it
off and can hear it making a sucking sound, the crankcase vent valve
is probably faulty. this is also common, The mixture faults can cause
O2 sensor faults. Chances are there is just a mixture problem. good
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