Oxygen Sensors - 98 DeVille

[crich8136]

Another P0155 problem:

98 DeVille, replaced the front head gasket last spring, rear gasket tested ok.

fuel gauge giving wierd readings (related or not?) When full it shows empty. Dings for the first 5 gallons. Then everything is normal until 4 gallons left at which time it is empty. But I can live with that unless it is related to my other problems.

Current PCM P0132, P0155

History PCM P0151, P0154, P0300, P0463, P1381, P1527, P1599

History PZM B0533, B1771

The car is hard starting and the exhaust smells bad. Sometimes when idling the RPMs swing widely, like 200 rpm or more. Other times they are stable. It now dies on me from time to time. This seems to happen when approaching an intersection and I assume that the idle just swung too low and it quit. It has backfired a couple of times and the other day it dieseled and delayed turning off.

When diagnosing the head gasket problem I broke one of a brand new set of spark plug wires and so replaced it with something from the salvage yard. Now thinking about buying a new set again anyway.

I am just at the stage of gathering information. Just purchased the 3 vol shop manuals for this car.

Called the Caddy dealer and the Olds dealer to price the O2 sensor and got different parts numbers. Would like to order from GMPartsDirect if I can find the right parts:

Bank 1 Sensor 1 -- part #25312203

Bank 2 Sensor 1 -- same part

GMPartsDirect also listed #25315373 (which one would be right?)

Olds dealer said: exhaust #25312211, engine out #25312197

Based on what I have been reading I am thinking of:

1. Check for disconnected ground wire G109 near the 'left hand rear corner of the engine, near the park/netural switch.' If the gound were left off wouldn't the other sensors show current errors? --

2. Check for blown fuses in the fuse box (by the air intake?) -- DONE

3. Replace the spark wires just so I know they are not contributing to the problem.

4. Replace the O2 sensors in the front and back exhaust manifolds.

(SevilleSTSJerome mentioned having to removed the coil and the blower motor just to have room to get to it. That sounds like going from the top of the engine. The manual talks about lowering the rear of the engine cradle 3 inches for this repair. Which is better?)

Thanks for any help you can give. I have learned a great deal from reading these forums.

Claude Richards