2001 SC1 problems

[NavyCPO]

Hi all,

I have a co-worker that is having problems with her SC1. I'm not sure if the mechanics she took it to for repair are being up front with her or trying to rip her off. I wanted to pose her symptoms and their diagnosis to you to see if she's getting the straight scoop.
First off, 2001 SC1 automatic with 44851 miles. She's the original owner. Code set: P0134.
Problems: high idle and extemely bad gas mileage(150 to 175 miles per tank). Also, Swish noise inside vehicle when braking.
Components replaced by mechanic: Idle Air Control Motor and both O2 sensors.
Recommended by mechanic: Replace PCM and program new PCM.
Side Note: ECTS has not been replaced.
* Symptoms of bad gas mileage(150 to 175 miles per tank) and high idle still exist even after components were replaced.
Questions: What year did the ECTS get changed to the Brass tip? Would it be possible that her 2001 would have the one with the brass tip already. If not I will replace it for her.
Thanks guys in advance. I just don't want to see her getting ripped off if, in fact, that is what is happening.
BTW, Mechanics shop is Carmasters Automotive LLC.

[NavyCPO]

More Info, since I didn't have an edit button.

From the print out that the mechanic gave my co-worker:

"Performed Scan with GM Tech II scanner, Found DTC P0134, followed flow chart, grounded 02S1 circuit did not go below 100MV, ungrounded and checked voltage, circuit had over 4.5 volts, then verified circuit 413 both rear 02 LO and ground from PCM to rear of engine. All circuit tested ok PCM providing excessive voltage, Both 02S were not cycling and reading high voltage."
"Recommend replace PCM and then check both 02S and converter for proper operation. Saturn/GM has extended emission warranties for PCM's. Recommend requesting free emission component repairs/replacement from dealer, If dealer does not provide, Carmasters can replace and flash program new PCM and perform follow-up testing."
I asked her if she was sure that they replaced both 02 sensors and now she "thinks" they only replaced the one off the manifold. I'm getting her to bring in the receipt and work order for that tomorrow.

What do the techs on here think?

[NavyCPO]

Additional info. My Co-worker called the mechanic to see which 02 Sensor they replaced and she was told that they have no record of them changing any 02 Sensor. So now she is going home to see if they charged her for work that wasn't performed.

Again thanks in advance for any shedding of light that anyone might have.

[Razorbak]

I think Saturn changed to the new brass-tipped ECT sensor design in 2001, but I'm not sure when exactly in the model year. The fact that her gas mileage is poor indicates a potential problem with the ECT sensor, but I don't know if that is sufficient in and of itself.

How is the dash temperature gauge reading during normal operation? If the sensor was broken and contributing to poor fuel economy, then the dash temp gauge should be very low, and the PCM should be overcomensating for the "cold" temperature by richening up the fuel mix and keeping the idle speed artificially high. Dash gauge readings will go anywhere from 1/4 to 3/4 during normal operation after fully warmed up, and the cooling fan behind the radiator should kick on when the engine starts running hot, but before the gauge gets to the red (dangerous) zone. My gauge reading hovers around 3/8 when warmed up, and the fan kicks on at about 5/8 to 3/4. Normal idle speed after warmed up is ~850 rpm +/- 50.

I checked my 1996 FSM, and the diagnostic flow chart for P0134 reads very similar to the tech's writeup posted above. There are several branches on the chart, and almost all of them include "Faulty PCM" as a possible alternative, but they also list "Terminal tightness", "Oxygen Sensor", "Open Ground Circuit", or "Open Signal Circuit" as possible causes. P0134 refers to "O2S circuit - Open/inactive". O2S is the code name for the front/exhaust manifold oxygen sensor. H02S-2 is the code name for the rear heated oxygen sensor.

[NavyCPO]

Thanks Razor for responding.
I will call her in a bit to see what her temp guage is reading and will post back with the Temp guage results. I'll also pull her ECTS to see if it is the brass one and if not will change it out. I hate to throw parts at a car that may not need changing but do you think it is worth it to go ahead and change the 02 Sensor on the manifold anyway?

[NavyCPO]

Razorbak,

Followup on the temp guage. She says that it stays steady at the 1/2 mark.

[Razorbak]

If it's reading 1/2 on the gauge, then it may NOT be the sensor, but that still doesn't explain the low gas mileage and the high idle. Go ahead and pull the sensor and check for the brass tip, if you've got time. And since there seems to be some confusion as to whether the O2 sensor was replaced or not, forget about the paperwork... just check it visually. If it WAS changed, the new part would be obvious. Old O2 sensors are almost always rusted in place, with the flats on the hex looking exactly like the rusty manifold. If it wasn't changed, then it may just need to be tightened. I hate to throw parts at something if it's not necessary. OTOH, the suggestion to try to get the PCM replaced under the extended warranty for emissions systems makes sense, as long as the mechanic can support his reasoning with his diagnostic troubleshooting. It can't hurt to check. What's the worst that can happen? If Saturn declines to replace the PCM under warranty, then she has another decision to make.

[NavyCPO]

Thanks Razorbak,

I will check the ECTS and the 02 Sensor tomorrow. Also will get her to check with Saturn for the extended emissions warranty as well. Will follow-up as soon as everything is checked.
I appreciate all of the help.

[ssicarman]

The code is for insufficient activety from the O2 sensor.

If the front o2 sensor has not been replaced yet I would replace it before even thinking about the PCM. It is extremely rare for them to fail. You mentiond that they were testing circuit 413. Not mentioned in the diag for the front O2 sensor. for the rear yes. not front.







DTC P0134




The oxygen sensor 1 (02S-1) is an electrical source that responds to oxygen content in the exhaust manifold. When the sensor reaches approximately 316°C (600°F), it produces a voltage based on the difference in oxygen between the atmosphere and exhaust gas. The powertrain control module (PCM) sends a bias voltage (391-491 mV) on the signal line which is pulled up through high resistance. When the O2S-1 is cold, it produces no voltage and has extremely high internal resistance. The internal resistance of the sensor is much greater than the resistance of the bias pull-up resistor. However, when the sensor heats up, it produces voltage that overrides the bias voltage. This voltage is read by the PCM to determine a rich/lean O2S-1 signal used to adjust injector pulse width. Under normal conditions, low sensor voltage means high oxygen content/lean air-fuel mixture and vice versa. Normal sensor readings will fluctuate between 10-999 mV. DTC P0134 sets when the O2S-1 signal is inactive, not fluctuating out of the 391-491 mV range.

DTC Parameters
DTC P0134 will set if O2S-1 is inactive -- voltage is not fluctuating outside the 391-491 mV range, when:

The condition exists for longer than 90 seconds.
The engine run time is greater than 1 minute
No camshaft (cam), crankshaft position (CKP), engine coolant temperature (ECT), exhaust gas recirculation (EGR), evaporative emission (EVAP) purge solenoid, fuel trim, intake air temperature (IAT), manifold absolute pressure (MAP), misfire, system voltage or throttle position (TP) sensor DTCs have been set.
DTC P0134 diagnostic runs continuously once the above conditions have been met.

DTC P0134 is a type B DTC.

Diagnostic Aids
DTC P0134 can set or cause false O2S-1 voltages if the oxygen sensor ground ( circuit 413) becomes loose or corroded. If circuit 413 becomes loose or corroded, bias voltage will be read on the scan tool and the voltage measured with a DVOM on circuit 412 at the O2S-1 harness connector (PCM side) will read over 1 volt.

To locate an intermittent problem, use the scan tool to monitor O2S-1 voltage with engine at normal operating temperature. Bias voltage (391-491 mV) will appear on the scan tool if the circuit is open.

The PCM will not go into closed loop if DTC P0134 has failed during the current ignition cycle.

[Mean Green SC2]

Originally Posted by NavyCPO

Hi all,


* Symptoms of bad gas mileage(150 to 175 miles per tank) and high idle still exist even after components were replaced.
Questions: What year did the ECTS get changed to the Brass tip? Would it be possible that her 2001 would have the one with the brass tip already. If not I will replace it for her.
Thanks guys in advance. I just don't want to see her getting ripped off if, in fact, that is what is happening.
BTW, Mechanics shop is Carmasters Automotive LLC.

My 2001 SC2 did not have ECTS with the brass tip.

I have an occasional high issue, which in my case, I believe is being caused by the tps. I'm not getting a code, but when the car is doing the high idle, I can tap on the sensor or jiggle the connector and it will return to normal. Just throwing that in because it would be very simple to check if you replace her ECTS.

[Mean Green SC2]

Originally Posted by Mean Green SC2

My 2001 SC2 did not have ECTS with the brass tip.

I have an occasional high issue, which in my case, I believe is being caused by the tps. I'm not getting a code, but when the car is doing the high idle, I can tap on the sensor or jiggle the connector and it will return to normal. Just throwing that in because it would be very simple to check if you replace her ECTS.

BTW, my gauge reading was normal (1/4 highway, 1/2+ in heavy traffic). I figured it was ok, but was trying to fix my high idle issue, thats why i replaced it. Still have the high idle, but did gain 10mpg on the highway.

[NavyCPO]

Update:

My friend called Saturn of Newport News last night and the PCM is covered under the extended warranty for emissions. But they told her they have to do their own diagnostics to ensure that the PCM is indeed bad. The charge for the diagnostic test is $80.00. I still have not had the chance to check her ECTS and 02 Sensor but will do that this weekend and will post my findings.

Thanks again for all of the responses.

[Luke]

>> Chief <<

Fm >> Razorbak <<

> Go ahead and pull the sensor and check for the brass tip, if you've got time. And since there seems to be some confusion as to whether the O2 sensor was replaced or not, forget about the paperwork... just check it visually.<

As a reminder, last year, I had a drop in my MPG, and found that my O-2 was the failing, but I determined that solely by reading my "SES" light while affecting a "road test". ((plugging in my cheap ($24.) code reader, while driving on the freeway)). BTW, upon close examination, it did not show signs, to my observations, to be contaminated. But, I don't have an expertise on "reading" O-2 sensors.

Replacing the unit, restored the MPG to my ususal results.

[Razorbak]

NavyCPO, please look at (or have your friend look at) the front O2 sensor and tell us if was replaced in this last service visit. It should be OBVIOUS through visual inspection. Just pop the hook and look down. Voila!!! Right now, the status of that part is still not certain.

[NavyCPO]

Originally Posted by Razorbak

NavyCPO, please look at (or have your friend look at) the front O2 sensor and tell us if was replaced in this last service visit. It should be OBVIOUS through visual inspection. Just pop the hook and look down. Voila!!! Right now, the status of that part is still not certain.

I've asked her to look at it and give me the status in the morning. As soon as I find something out I will post the results.

Again Thanks Razorbak for all of your help.

[NavyCPO]

Razorbak,

Update: She checked to see if the 02 Sensor was changed and it wasn't. She is willing to buy a new one to replace it. The question I have before she does that is, Is there any thing that can be done with an 02 Sensor to see if it is bad, visually (like an ECTS, cracked resin tip) or electrically (ie; multimeter)? Or should she just go ahead and let me replace it? I'm replacing her ETCS this weekend.

Thanks again!

[Razorbak]

Originally Posted by NavyCPO

Razorbak,

Update: She checked to see if the 02 Sensor was changed and it wasn't. She is willing to buy a new one to replace it. The question I have before she does that is, Is there any thing that can be done with an 02 Sensor to see if it is bad, visually (like an ECTS, cracked resin tip) or electrically (ie; multimeter)? Or should she just go ahead and let me replace it? I'm replacing her ETCS this weekend.

I'm not aware of any inspection technique that will tell you whether the O2 sensor is bad, but that may simply be my ignorance. Since ssicarman suggested changing the O2 sensor, I would follow his advice.

[NavyCPO]

Originally Posted by Razorbak

I'm not aware of any inspection technique that will tell you whether the O2 sensor is bad, but that may simply be my ignorance. Since ssicarman suggested changing the O2 sensor, I would follow his advice.

Thanks, I have already talked to her and she want's to go ahead and change out the ECTS and the 02 Sensor. Will be doing that for her this Saturday and I will post the results as far as the high idle is concerned. The gas mileage results will take a bit to get but I will be sure to post them as soon as I can get them. Also have a question as far as the Idle Air Control Motor goes. Do you think that they changed the part for no good reason? What code would that have given? The only code that they documented was the P0134 code.
Also, any idea as to what the swishing noise inside when braking could be? And what do I need to check for?

[Razorbak]

You said she was experiencing a high idle problem, and they replaced the Idle Air Control valve. Whether the latter was faulty and causing the high idle was not really determined. If replacing it did not cure the problem, then it's fair to say that it was not the cause. The ECT sensor may be solely to blame.

FWIW, you also said they replaced both O2 sensors, but she verified visually that they did not replace the front sensor. Sounds like you have grounds for at least one overcharge component, and possibly two.

Don't know about the swishing noise upon braking, but my heater coil makes a similar swishing noise when I accelerate hard in low gears. I think it's just the sound of coolant rushing through the heater coils as the crankshaft accelerates through the rpm curve and drives the water pump faster (i.e., creating a bit of turbulence in the heater coil).

[NavyCPO]

I agree with you on the refund. I doubt she will go back and try and get a refund but chalk it up to a learning experience. The sad thing is the place was recommended to her by a friend. I am in the process of teaching her to do some of the basics herself ie; plugs, air filter, ECTS and 02 Sensor and if she feels comfortable enough, oil and filter change.
I'll let her know about the swishing as well.
Thanks for all of your help Razorbak and i will be giving a follow up this Saturday.