o2 Sensor problem

[sailorjaycope]

My check engine light has been on and off for a few weeks now so I had the dealership check it out. Apparently its a problem with the "1/2 o2 sensor voltage high." I declined the service at the time since I was already dropping 300 for the tune up!!!!!!! Has anyone else experienced this problem or know the seriousness of it? Hopefully it won't be too costly!!! Happy holidays everyone!

[CUEBALL]

<bump>............

[Rambit]

Obviously this is a dealer problem, but here's what it says about that condition. As you can see, it can be one of six things, ranging from a short, the O2 sensor itself or the PCM. In any case I don't think it's a serious problem otherwise the dealer would have cautioned you not to drive your car.

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When Monitored:
O2 Sensor Heater Temperature is greater than 496°C (925°F) and battery voltage greater than 10.99 volts.

Set Condition:
The Oxygen Sensor voltage is above 3.7 volts for 30 seconds. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes

• (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
• (K904) O2 DOWNSTREAM RETURN CIRCUIT SHORTED TO BATTERY VOLTAGE
• (K141) O2 1/2 SENSOR SIGNAL CIRCUIT OPEN
• (K904) O2 DOWNSTREAM RETURN CIRCUIT OPEN
• O2 SENSOR
• PCM

Diagnostic Tests

1. O2 SENSOR ABOVE 3.7 VOLTS
NOTE: When only one O2 Sensor is shorted to voltage, the scan tool will display all O2 Sensor voltage readings at approximately 5.0 volts. When diagnosing this DTC, only diagnose the O2 Sensor that set the DTC.
Start the engine.
Allow the engine to reach normal operating temperature.
With a scan tool, read the 1/2 O2 Sensor voltage.
Is the voltage above 3.7 volts?
Yes >> Go To 2

No

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE -STANDARD PROCEDURE)

2. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Start the engine and allow the engine to idle.
Disconnect the 1/2 O2 Sensor harness connector.
Measure the voltage on the (K141) O2 Sensor 1/2 Signal circuit in the O2 Sensor harness connector.
NOTE: Measure the voltage in reference to ground, not the (K904) O2 Downstream Return circuit.
Is the voltage above 5.2 volts?
Yes >> Repair the short to battery voltage in the (K141) O2 Sensor
1/2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No

>> Go To 3

3. (K904) O2 DOWNSTREAM RETURN CIRCUIT SHORTED TO BATTERY VOLTAGE

Turn the ignition off.
Disconnect the PCM harness connectors.
Ignition on, engine not running.
Measure the voltage on the (K904) O2 Downstream Return circuit in the O2 Sensor harness connector.
Is there any voltage present?
Yes >> Repair the short to battery voltage in the (K904) O2 Downstream Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No

>> Go To 4

4. O2 SENSOR

Turn the ignition off.
Connect the PCM harness connectors.
Connect a jumper wire between the (K141) O2 1/2 Signal circuit and the (K904) O2 Downstream Return circuit in the 1/2 O2 Sensor harness connector.
Ignition on, engine not running.
With a scan tool, monitor the 1/2 O2 Sensor voltage.
Is the voltage between 2.3 and 2.7 volts with the jumper wire installed?
Yes >> Replace the O2 Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No

>> Go To 5

NOTE: Remove the jumper wire before continuing.

5. (K141) O2 1/2 SIGNAL CIRCUIT OPEN
Turn the ignition off.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K141) O2 1/2 Signal circuit from the O2
Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 6
No

>> Repair the open in the (K141) O2 1/2 Signal circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6. (K904) O2 DOWNSTREAM RETURN CIRCUIT OPEN
Measure the resistance of the (K904) O2 Downstream Return circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 7
No

>> Repair the open in the (K904) O2 Downstream Return circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer

to 9 - ENGINE - STANDARD PROCEDURE)

7. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE -STANDARD PROCEDURE)
No

>> Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE -STANDARD PROCEDURE)

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Bernie

[sailorjaycope]

thanks for the info Rambit. Much appreciated.

[mpouls1]

Kind of depends on how many miles you got on the car. I'm no mechanic but I have changed a couple of O2 sensors on my cars before. Usually when the code goes just means you need to replace it. If not, your gas mileage is just a little worse than it should be.

Probably wouldn't be to hard for you to change either. Just go to autozone and they sell a special socket that is used to pull it out of the exhaust. It just connects to a socket wrench. Sensor may be a little expensive though. Maybe 70-100 bux, dunno just ballpark. But I have changed them on a couple different cars. Not sure but I would believe your car would have 2 of them, so better to do both, than just one.

If you do do it yourself, be sure to warm the car up first before trying to pry them out. They can be a b*&%h to get out. Just be sure to not burn yourself.

[Rambit]

Yeah, he's in kind of a damned if you do, damned if you don't situation cuz he's probably off warranty by now. Either way he goes it's going to cost to have it diagnosed by the dealer, or he changes parts without knowing what the problem is, hoping to get lucky.

Now I'm wondering if the O2 sensor is considered part of the emission system. If it is I believe it has a 5 year warranty. Humm???

Bernie

[mpouls1]

As stated previously, I am not a car mechanic, but I have torn some engines apart and what not, but I believe you are supposed to have them replaced every 70-75k miles anyways to improve your fuel efficiency. My gut says his sensor reading high means that it is just old and needs to be replaced. So, high mileage, just replace. Low mileage, maybe another story.