Hello,

I've been doing a lot of driving the back roads and looking in the woods for some trees. Rather than start and stop and run the battery down and risk not having enough to start the car again I mostly leave the car running on the side of the gravel road while I poke into the woods for a few minutes and look around. When I get back to the car it will trigger a oxygen sensor code and the check engin light stays on. If I reset, the light will trip back on within half a day or two. Only ever at idle.

Not enough to make me want to buy a new oxygen sensor for 100 + $

But can anybody recommend a quick fix that has squeezed a bit more life out of their sensor or connections ?

I had the sensor out of the muffler pipe last winter when I needed to weld the downpipe at the Y. Threads looked good and so did all the connections. It started doing this a couple months ago.

Any tests or checks I could do to trouble shoot this problem?

can you afford 10 bucks and bits of splicing the new one into the old harness?

http://www.ebay.com/itm/360897131426

Do you know how to check the heater?
--
Art Benstein near Baltimore

If speed counted, rabbits would rule the world.

Hi Art,

No I don't know how to check the heater.

What would that do for the tripped check engine light for an O2 sensor signal code ?
I'm curious ..

Hi jonny2box,

Sorry to be so cryptic. I figured you would answer quickly as you had just posted when I replied. Of course, I meant the heater in the oxygen sensor. An oxygen sensor like yours depends on the heater function.

The sensor is heated by a resistive element powered by the fuse 4 circuit along with the tank pump. A quick way to determine whether it works is to measure its resistance shortly after disconnecting it on the running car. The connection where you measure it is below the wiper motor -- a two pin junction with white wires leading to the sensor.

Measuring the resistance immediately after disconnecting it, toward the sensor of course, will show a reading in the neighborhood of 13 ohms, and as it cools you will see the resistance dropping toward a cold value of about 4 ohms. That test assures you the heater is intact and its power source valid. The test takes about 5 minutes.

If the heater does not respond as above, you would check to see it is getting powered before replacing the oxygen sensor.

By the way, I was not available to check your thread yesterday as I was under a car replacing the downpipe. I welded the Y and the holes around the midpoint brace back in Oct. 13, but now the whole aftermarket pipe is like Swiss cheese. Frankly I was surprised my welding (using oxyacetylene and coat hanger for filler) lasted that long.


--
Art Benstein near Baltimore

SUCCESS:
At age 4 success is . . . not peeing in your pants.
At age 12 success is . . . having friends.
At age 16 success is . . . having a drivers license.
At age 20 success is . . . going all the way.
At age 35 success is . . . having money.
At age 50 success is . . . having money.
At age 60 success is . . . going all the way.
At age 70 success is . . . having a drivers license.
At age 75 success is . . . having friends.
At age 80 success is . . . not peeing in your pants.

Hi jonny2box,

I believe Art B. is providing you some suggestions into how to test the 02 sensor.

If the brickboard.com search feature is feeling more of less fussy than usual, as the vacuum tubes have heated up, you can use the brickboard search on this half of the forum (RWD) to find tips how to test and verify whether your 02 sensor has failed.

You'd need a few tools like a multimeter. About 7$ to 15$ from Harbor Freight.

Please search this board on how to test the 02 sensor.

Yet agreed with trichard that the 02 sensor has failed.

And when you checked the OBD, you checked for faults in socket 6 (fuel injection) and socket 2 (ignition).

Like trichard recommends, a splice-in replacement 02 sensor. The choice is Robert Bosch. On your search of this board, you may find various Bosch 02 sensors, such as a splice in. Should yopu choose a splice in, you'd be best to solder the single 02 wire and the two heater wires, and use shrink wrap and an adhesive sealant okay for the under the car conditions while next to the header pipe. If you can swing a plug and play Bosch 02 sensor, that would be best.

Please shop around. You can check the stalwarts FCP Groton and iPd for replacements, as well as trichard's suggestion on eBay and I think Amazon.

You may want to contact your local brick and mortar auto parts store. Shop around.

You do have choices on oxygen sensor brands other than Bosch. I have read on many forums that these may not be choice or last as long. Some may.

From Parts Geek:

Buy a 1990 Volvo 240 Oxygen Sensor at discount prices. Choose top quality brands Beck Arnley, Bosch, Delphi, Denso, Standard Motor Products, Walker …

http://www.partsgeek.com/catalog/1990/volvo/240/fuel_injection/oxygen_sensor.html

You have some 40+ Ebay auctions as trichard aforementions.

If using anti-seize compound on the thread, must be free of lead and silicon.

I'm a little worried you making mention you had to weld the header pipe. On a 1990 240, the 02 sensor fits into the fore end of the catalytic converter.

How is the lower header pipe support? There is a bracket assembly that supports the header pipe, or hangs the header pipe from a bracket secured to the bell housing. This support is critically important. The corresponding interface between the header pipe output to the catalytic converter must be wholly sealed. That exhaust union requires that bracket support.

The emission systems comprising the engine control on the Volvo 240 actually work best with all emissions controls working. The 240 responds well and sprightly in good tune.

Please avail your self to the brickboard to perform more research so you can further perform diagnosis and repairs that may cost you only time, and maybe a multimeter.

For example, today, on my 1992 240, I had a small vacuum line split at the PCV valve flame trap sieve. While there, I remove the air intake piping between the air filter box and the throttle body. Found a hole in the accordion-like hose between the air mass meter (some call it a mass air flow sensor) output and the throttle body input. Used a flashlight in a dark room to find the whole in that hose. Got some new PCV vapor line, about 4.8 millimeter inside diameter. Teh 25 year old vacuum hoses are quit brittle. I also pulled and reseated all connectors to sensor, devices (injectors, idle control motor, the ignition power stage ...) while there. Loosed and secure some ground connections. Removed the power the ignition power stage, separated the IC amplifier from the aluminum heat sink, cleaned th heat sink interface, and applied new thermal paste compound (like that used between a computer processor and the heat sink assembly). Inspected the air filter and it was okay. (The odometer is broken and in three tries I'm not able to make it work, though the first repair attempts cured code 3-1-1 from socket six, ignition.)

If the brickboard.com search does not work, use the Google search engine, (cause Microsoft Bing is useless). In your Google search query, add:

site:www.brickboard.com

or

site:www.brickboard.com/RWD/

With your search query.

The 02 sensor is a well-treated topic here.

Yet I would also urge you to study the FAQ (click FAQ on this page, up top) as the 700 series and early 940 series Volvos shared the four cylinder engine and the control systems with same year 240s. Engine control sensor and devices are well covered.

Also, you may find a Bentley, Haynes, or other Volvo service manuals for free or used at a book store, and elsewhere.

Since I have no life, stolen away from me 25 years ago while attending CSU, Chico, I can write these long posts.

Questions?

Hope that helps.

MacDuffed Sundays.
--
The Volvo 164: The Mightiest of All Volvo Automobiles in Perpetuity