Hi, all,

Are Bosch Platinum+4 spark plugs (FR 7 DC) the right type of plugs for 1995 850 (non turbo)? The reason I am asking this question is that my car's check engine light came on about 10 days after they were installed. I don't know whether it was just a coincidence. I purchased those plugs online (www.foreigncarpartsonline.com). Thanks in advance for your response.

PG

PS: I replaced them with the Volvo spark plugs after the check engine light came on.

i am running on bosch 4+ about 8 months now, and did not have any problems so far (knock-knock-knock). they are not recommended to be used on electronic coil ignition, but should work fine on volvo's ignition system.
i noted improvement over oe plugs.
I think your light is not related to spark plugs.

Why don't you pull the code(s)?

Thanks for your message.

I did pull the code. It was 435 (? Heat O2 sensor slow response?). The check engine light stayed on even after I changed the spark plugs to Volvo ones. I cleared it last weekend and see whether it comes back. I will get the sensor replaced if the check engine light comes back on.

PG

I doubt that the Bosch +4's would cause an O2 sensor problem on their own. Instead of replacing the O2 right away, try removing it from the exhaust piping, heat the housing that goes into the pipe until it glows orange, and keep it that hot for atleast 3 minutes. Let it cool, then spray it down with a non-chlorinated brake cleaner, doing your best to get the brake cleaner in and out of the openings. Repeat the heating and brake cleaner steps twice, the final time not using any brake cleaner. Reset the code, and see if it comes back.

A large majority of the time, when O2 sensor codes occur, ESPECIALLY slow response codes, it is the result of contamination from dirty fuel. This heating and brake cleaner cleaning often clean the O2 sensor out very well. About a year ago, I had my light come on reporting the same thing. I did what I prescribed, and the O2 sensor light didn't come on for about 10 months. After that, the cleaning no longer worked, but considering the sensor was about 4 years old, I wasn't complaining.

Thanks again for your message.

At this point, I simply reset the error code (last week) and want to see whether the light will come back on. If it comes back, I will do something to the O2 sensor.

I read one of your previous posting that describes the method of cleaning up the sensor. After reading your this message, I am confused. In your previous posting, you were saying to torch the sensor. In this one, you are saying to clean up the house. Which one is correct or both should be cleaned?

Sounded you did the job yourself. Is it easy to remove the sensor? Did you unplug the sensor wire?

PG

Have you checked the owners manuel to see what it says? My local Volvo dealership says to avoid using platinum plugs. They will mess up the computer. Use the standard plugs that are listed in the owners manuel for best performance.

food for thought.

Rick 97 850-R

Thanks for your info. I replaced the Platinum plugs with the regular Volvo ones about two weeks after the Platinum plugs installed. For my car, I did not notice big difference in performance in using the two different plugs.

PG

...My T-5R Ran Like $#)@ when I Relaced With Bosch Platinum 4's...Went
to Volvo, Used the Recommended...It Was Immediately Noticeable!!!...Crazy
But TRUE!...Wouldn't Believe It If It Didn't Happen to Me!...AL.

Hmmmmm, maybe I'll try that too. Does anyone have a Bosch number for the standard oem replacement(non-platinum)?
Over, Tim

Absolutely! This is straight out of the manuel.

Non-Turbos Bosch: FR 6 DC (or equivalent)

Turbos: Champion RC7GYC (or equivalent)

Gap: 0.028" (0.7 mm)

Tightening torque: 18.4 ft lbs +or-3.7
25 Nm + or - 5 Nm

hope this helps.

Rick 97 850-R