"03" Saturn Ion M.A.P;Range and o2 sensor advice needed

saturn

#1

I need some advice.Took my car into autozone today to have them scan for error codes.Was told that 3 codes were showing up.One for the manifold absolute pressure sensor(Or,M.A.P.S),one for the range performance sensor (This sensor,he said,was shorted out) and one for the “bank one” oxygen sensor (Which he also said was shorted out (I think he said it was showing high voltage usage or,that it was shorted out due to high voltage ?) He then told me also,that I should replace the M.A.P sensor first.

First,WHY would these sensors “short out” ? And,if I replace them,is this going to happen again ??? I’ve found one or two (?) of our dogs had something trapped underneath the car at night on at least a couple of occasions.Funny thing,though…I’d never heard any sounds coming from underneath the car when the dogs had done this.And,2-3 times I had found bits of wires in the gravel (Hard to spot there,too) that look like they had been chewed on or ripped out by an animal.Is it possible that a racoon (Or,something) got trapped by our dogs under there and the animal was just nervous or,scared and started chewing on wires ?? Could that have caused these issues ?

Nothing really seems to be wrong with the car other than that engine light coming on intermittently.Well…sometimes the idle fluctuates (Which I understand can be related to the o2 sensor.And,one last question…(Okay,maybe two)…Is this “bank one” oxygen sensor the upstream sensor or,the downstream sensor ? I ask this because I think it’s importan when ordering the part ?

Any advice any of you could give regarding this matter would be immensely appreciated !!


#2

All Saturn Ions have 4 cylinder engines so you have only 1 bank which is Bank 1.

It would be helpful if you would post the specific error codes that Auto Zone read from your car.

But from the information given I suggest that you look closely for a vacuum leak that would affect the MAP sensor. Inspect all the vacuum hoses and connections and all the gasket joints. A problem with the MAP will cause the engine to run too rich or to lean which the O2 sensor would detect and cause a code indicating a problem with the O2 sensor when there may not be one. Correcting the MAP problem should be taken care of first.


#3

Concur, don’t worry about the O2 code until the MAP sensor problem is resolved.

I don’t know what your car’s range performance sensor is or does. As suggested above, post the actual ECM diagnostic codes so you can get the most benefit from the car-repair knowledgeable folks who respond here.

MAP means Manifold Absolute Pressure. It is a sensor that measures the intake manifold pressure, not in relative terms w/respect to the ambient air pressure (barometric pressure), but w/respect to a complete vacuum. It’s done that way so the computer can better accommodate altitude changes, like if you live in the lowlands but sometimes drive in the mountains. The computer can make the needed adjustments so the engine continues to run smoothly at either altitude.

The MAP sensor reading is also used to estimate the amount of airflow into the engine, and is used in conjunction with other sensors like the throttle position sensor, engine coolant temperature sensor, vehicle speed sensor, etc to estimate the baseline flow rate of fuel to inject for that driving condition.

The O2 sensor is sort of a fine-tune adjustment which allows the computer to start with the estimate above, then make slight adjustments to the fuel flow rate to get the air fuel mixture %'s exactly correct. But it is also a double-check on the baseline fuel flow rate calculation; for example if the O2 sensor shows the estimated fuel flow rate calculation is actually way too much fuel, there’s either something wrong with one of the baseline calculation sensors or with the O2 sensor.

My Corolla’s MAP sensor has two inputs, a precision + 5 volts, and ground. And one output, the sensor voltage, which varies between ground and + 5 volts depending upon the pressure. If one of those wires got chewed up by a squirrel or raccoon, or got broken in a disagreement between one of those creatures and your dogs, that would cause the sensor to register incorrectly and flag a diagnostic error code. Should be a simple matter for a mechanic to trace all three of those wires.


#4

Varmints chewing on wires is very common. O2 sensor wires are very exposed and damage should be visible if near the sensor.


#5

Hey guys…thank you all very,very much for all the info ! And,Rod Knox…love that name ! Ha,ha,ha.I’ll come back laer with an update.And,again…THANK YOU !!!