95 850glt rear O2 sensor question:

Do you know what the specific code number is? The system should be able to tell the difference between a bad secondary O2 sensor and a bad catalytic converter... whether it will tell you clearly which one it is is another story.

But just playing the odds, I'd lean toward the catalytic converter. Just not enough lean to tell you to spend your money yet! (Normally, front O2 sensors give more trouble than rear sensors.)

Mike

the code given was 4-3-5-heated o2 sensor response slow

Yep - that is pretty sensor specific. Slow response is a common failure mode for O2 sensors.

The wire-in type should work as well as the one with the connector. I've used one (on a Nissan) and it was fairly easy. The one I bought didn't come with splices so I had to supply those, but I think many come with splices ready to go now. It just re-uses the connector from the original.

Mike

435: Heated Oxygen sensor (HO2S), Front Slow If you have access to a scan tool monitor the front O2 Sensor as the engine heats the voltage should go up & down I can not remember the exact voltage I think it is the range 0.30 Volts to a high of 1.0 Volts if it does not move or moves very slowly you need to replace the front O2 Sensor Volvo sells a service kit that installs a cable in line you might want to try this first before changing the front O2 Sensor Glenn Volvo Master Technician ASE Certified Automotive Technician

there are 2 sensors on the '95 850glt right? so the 435 code indicates the front? just want to be sure b4 i spend any money. i thought the front sensor in general on most vehicles was not heated b/c the engine heated the exhaust manifold quickly enough so that the signal would be accurate. Of course I am just learning here, so if someone can clear that up it would be great. Or if Glenn could elaborate, it might clear my head on it. Thanks! robbie

My (layman) understanding is that the front O2 sensors are heated now (maybe part of the OBD II requirements?) to bring the system into "closed loop" operation as soon as possible.

Mike

The Front Heated O2 Sensor I am Looking @ the code Book as I type HO2 Sensor = Heated Oxygen Sensor Glenn

On federal spec cars the O2 sensor has had a heating coil built in since

1984. The EPA reg at that time required the O2 sensor to be at operating temperature in something like 45 seconds after start, well before closed loop operation in something like two minutes after start.

Bob

Unless they are flat worn out most O2 sensor codes sre caused by vacuum leaks. On '95 model 850s most notably be the rubber adaptor fitting in the center of the giant welch plug at the end of the manifold just behind and hidden by the power steering reservoir. Spray some gum cutter or brake clean down the end of the intaske manifold with the motor running and see if the idle speed changes. If it does hie thee to the nearest Volvo dealer for a replacement fitting. You'll probably have to remove the power steering pump to gain access, but it can be done without removing the pump.

Bob

Thanks!

Mike

What you are describing always sets ECM232

True, but 232 is almost always there anyway.

Bob

on fcpgroton.com their 1995 850 front 02 sensor shows 2 different parts- 1 for cars with an air pump and w/o a pump- how do i tell if mine has an air pump? thanks!