My 'Check Engine' light came on yesterday morning. Since I just bought this beast 2 weeks ago, I thought, "Oh great, what did I get myself into...."

Anyway, my code reader indicated a P0147, O2 Sensor Heater Circuit Malifunction (Bank 1 Sensor 3). I have a subscription to ALLDATA which has provided valuable information, but I was wondering if anyone has had any experience in this DTC and if there are any caveats as to fixing the sensor issue.

As I was reading through the ALLDATA info, I came across this:

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Service and Repair

REMOVAL PROCEDURE

TOOLS REQUIRED
J 39194 Oxygen Sensor Wrench

NOTE: Do not remove this pigtail from either the heated oxygen sensor (HO2S) or the oxygen sensor (O2S) . Removing the pigtail or the connector will affect sensor operation.

Handle the oxygen sensor carefully. Do not drop the HO2S. Keep the in-line electrical connector and the louvered end tree of grease, dirt, or other contaminants. Do not use cleaning solvents of any type.

Do not repair the wiring, connector or terminals. Replace the oxygen sensor if the pigtail wiring, connector, or terminal is damaged.

This external clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors, or terminals could result in the obstruction of the air reference and degraded sensor performance.

The following guidelines should be used when servicing the heated oxygen sensor:

* Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance.
* Do not damage the sensor pigtail and harness wires in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.
* Ensure the sensor or vehicle lead wires should not be bent sharply or kinked. Sharp bends or kinks could block the reference air path through the lead wire.
* Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will cause poor engine performance.
* Ensure that the peripheral seal remains intact on the vehicle harness connector in order to prevent damage due to water intrusion. The engine harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed.

The Heated Oxygen Sensor (HO2S) may be difficult to remove when the engine temperature is below 48°C (120°F) . Excessive force may damage the threads in the exhaust manifold or the exhaust pipe.
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I am confused somewhat by the bold statement since it seems like one should just replace the sensor! I will follow the test procedures that ALLDATA provides to narrow down the problem, but if anyone has any other advice, I'd love to hear it.

Thank you,

Allan

 

If it's the B1S3 sensor, then it is the one behind the main Catalytic converter. I would clear the code and see if it comes back again. If it does, replace the sensor. It is an emissions only sensor and it doesn't have anything to do with the engine controls.

*EDIT* - whoops, too quick to hit the post button...

Anyway, No real special handling instructions for replacing the O2 sensors. You obviously don't want to get anything on the sensor head. You shouldn't need any special tools, only something like a 20mm wrench (or is it a 24mm...??? - can't remember) on the Blazers. You can get to the sensor with an open ended wrench. Make sure that you apply some anti-seize to the threads of the new sensor and ONLY the threads. Make sure that there is no way that any anti-seize can get onto the sensor head.

If you can't get the sensor out with a reasonably firm hand on the wrench, it may be necessary to heat the sensor bung on the exhaust pipe. The last thing you want to do is to break the bung off of the pipe (unless you know how to weld and have access to a welder). You could do this or warm up the truck (by running it) and then thermo shocking the sensor with a cold, wet rag as close to the hex on the sensor as you can get.

Good Luck

 

Okay, thanks for the info. I will reset the code in the morning and go from there. My other car is an '81 Volvo wagon with a carb so I need to familiarize myself with these crazy, modern electronics .

Allan

 

You can disconnect the senor and the truck will run. The puter is programmed to go into a default mode. The problem with running around in the defualt mode is your fuel mileage will suck big time.

 

Not true. B1S3 is the rear most sensor and has NOTHING to do with engine management. It is an emissions only sensor and tells the PCM that the cat is operating properly.

 

Well, I reset the code this morning and made several trips around town today. It has yet to come back on. I also checked with my reader at the end of the day and there were no 'pending' codes either.

Thank you all for the info.

Allan

 

It's a crap shoot as to if it will come back or not. It could have been a fluke, but more than likely, it was not.

The drive cycle reset for that code is approximately 3 heat cycles (ECT below 100*F to ECT above 170*F and back down is a cycle), and over 30 miles (or something like that on the miles). Oh and like 5 key-ons as well. The emissions check will be incomplete until it has gone through all of the above.

You have to remember that if your state/region uses the emissions readiness status stored in the PCM, then if you clear your codes, you will not pass until the drive cycle has been fully completed and the inspection station will know that you had just reset your codes. If you have problems, get them fixed well prior to having it inspected.

 

You're right... time will tell. But at least I know what it is and how to fix it .

I live in Vancouver, BC, Canada and we have a thing called AirCare (read just another tax for us since the rest of the province doesn't have it). In order to get your insurance, you have to pass AirCare. For '92 and newer, ever 2 years, you need to take it through the testing centre. For '91 and older, every year. They run an IM240 test and whether the codes have been reset or not, they don't care. In fact, your chances of passing the dreaded AirCare test improves depending on which testing you go to! Crazy, yes I know, but don't ask. Many people in the Greater Vancouver area HATE AirCare and view it as a massive government pork barrel wasting our money... sorry, ranting there.

Again, thanks for all the help.

Allan