Service Engine Soon - 96 Chevy Truck

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1996 Chevy Silverado, 5.7L, Service Engine Soon light came on/off for
a day or two...now is staying on.  I had a local auto parts store
perform OBD check and po155  [O2 Sensor Heater Circuit Malfunction
(Bank 2 Sensor 1)] and po175 [System too Rich (Bank 2)] codes were
listed.  The plugs, wires, rotor button, rotor cap, air and fuel
filters and pcv valve have all been changed within the last 3-4
months.

Is this a problem with the O2 sensor(s) or something with the throttle
body?  Any help with diagnosis and/or solution would most appreciated.

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Re: Service Engine Soon - 96 Chevy Truck


cookiemonster wrote:
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prolly your O2 sensor(s). I have a 96 also and I just replaced them this
winter. The "book" says to replace them every 30K, yeah right. DO NOT
get the "universal" style. Spend a few extra bucks and get the ones that
plug right in. IIRC they were $60-65 each online. Make sure you know
which plug style you are replacing. There is an in line and a four
square type.
Mike

Re: Service Engine Soon - 96 Chevy Truck


I would focus on the heater circuit first, first check the fuses for the o2
sensor, if ok you must get a wiring diagram to check the heater circuit to
the sensor to determine if the sensor itself is bad, most likely this is the
problem, there is some chance that may also correct the 0175 problem, when
fixed clear the codes and see.
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Re: Service Engine Soon - 96 Chevy Truck


I had a similar problem on a 96 Tahoe. 5.7L Engine was running rough and the
MIL lamp came on. Turned out to be a bad fuel pressure regulator.

Good Luck,
TJ

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request
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692.html
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Re: Service Engine Soon - 96 Chevy Truck


"cookiemonster" wrote:
 > 1996 Chevy Silverado, 5.7L, Service Engine Soon light came
 > on/off for a day or two...now is staying on.  I had a local
 > auto parts store perform OBD check and po155  [O2 Sensor
 > Heater Circuit Malfunction (Bank 2 Sensor 1)] and po175
 > [System too Rich (Bank 2)] codes were listed.  The plugs,
 > wires, rotor button, rotor cap, air and fuel filters and pcv
 > valve have all been changed within the last 3-4 months.
 >
 > Is this a problem with the O2 sensor(s) or something with the
 > throttle body?  Any help with diagnosis and/or solution would
 > most appreciated.

I replaced the forward O2 sensors on both sides.  That fixed the
’service engine light’.  Thanks to Mike, Shep2 and TJ for your input.
However, the truck still idles a bit rough.  Any ideas?  Thanks again
for your help!
CM

Re: Service Engine Soon - 96 Chevy Truck



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yes

what part of 'HEATER CIRCUIT MALFUNCTION' is so difficult to understand ?




Re: Re: Service Engine Soon - 96 Chevy Truck


"" wrote:
 > > "cookiemonster" wrote:
 >  >  > 1996 Chevy Silverado, 5.7L, Service Engine Soon
 > light came
 >  >  > on/off for a day or two...now is staying on.  I had
 > a local
 >  >  > auto parts store perform OBD check and po155  [O2
 > Sensor
 >  >  > Heater Circuit Malfunction (Bank 2 Sensor 1)] and
 > po175
 >  >  > [System too Rich (Bank 2)] codes were listed.  The
 > plugs,
 >  >  > wires, rotor button, rotor cap, air and fuel
 > filters and pcv
 >  >  > valve have all been changed within the last 3-4
 > months.
 >  >  >
 >  >  > Is this a problem with the O2 sensor(s) or
 > something with the
 >  >  > throttle body?  Any help with diagnosis and/or
 > solution would
 >  >  > most appreciated.
 > >
 > > I replaced the forward O2 sensors on both sides.  That fixed
 > the
 > > 'service engine light'.  Thanks to Mike, Shep2 and TJ for
 > your input.
 > > However, the truck still idles a bit rough.  Any ideas?
 >
 > yes
 >
 > what part of 'HEATER CIRCUIT MALFUNCTION' is so difficult to
 > understand ?

is it necessary that the rear o2 sensor be screwed in . I am missing
the caty and  muffler. will this cause the engine light to come on.
All sensor have been replaced!

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Re: Service Engine Soon - 96 Chevy Truck


"cookiemonster" wrote:
 > 1996 Chevy Silverado, 5.7L, Service Engine Soon light came
 > on/off for a day or two...now is staying on.  I had a local
 > auto parts store perform OBD check and po155  [O2 Sensor
 > Heater Circuit Malfunction (Bank 2 Sensor 1)] and po175
 > [System too Rich (Bank 2)] codes were listed.  The plugs,
 > wires, rotor button, rotor cap, air and fuel filters and pcv
 > valve have all been changed within the last 3-4 months.
 >
 > Is this a problem with the O2 sensor(s) or something with the
 > throttle body?  Any help with diagnosis and/or solution would
 > most appreciated.

I thought I had it fixed.  

I replaced the front (before catalytic converter) two O2 sensors since
they are the only ones that influence fuel settings/flow.  The engine
light went off and stayed off for a couple of days.  However, it was
still idling a bit rough.

Engine light has come back on with code "P0175  System too Rich (Bank
2)".  Any ideas what this could be?  If it was the fuel pressure
regulator problem, wouldn’t both banks (right and left) run too rich?
Any suggestions or direction appreciated.

CM

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