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Good Afternoon All !!!
We have a 1993 Volvo 850 here, we scanned it and it had a MAF Code.

Got in a new MAF Sensor and installed but car would not start, disconnect the MAF Sensor car starts, runs and idles; put old MAF Sensor back in Car will start and run but sets a MAF Code again, Repaired some leaking vacuum lines and reset the computer, No Change.

Not Sure where to go now???

Gale

New sensor from where?

It was a new Bosch Sensor from World Pac, with I initially called the Volvo Dealer and Got the part number and confirmed that it was a bosch MAF Sensor
and he said that they are the same other then packaging, if that is true or not I'm not sure.

I'm not certain but think there were 2 different engines that era and they used different sensors. What was tested to determine the sensor was bad initially?

brianp87 wrote:I'm not certain but think there were 2 different engines that era and they used different sensors. What was tested to determine the sensor was bad initially?

You are correct. One used a hot wire sensor and the other used a thick film sensor.

When I called the Dealer to check on the part, I gave him the serial number, so I'm assuming from that he should have been able to give me the Correct number "I would hope" and when it came in it looked exactly the same as the one we took out, but I guess the question is the one we took out the correct one, but the car does run on the old one.

After Doing some more checking the MAF Sensor that is in the Car is the Hot wire Sensor. John ran voltage tests on all the wires going into the Sensor Etc... and everything tested normal, which should indicate a faulty Sensor, so after we got the new one and installed it would not run, could nit get started, installed the old one and it started and ran. tried it a few times cause it seemed odd. but then customer picked up the car cause we said it was running with the old one, that was on a Friday, he called Monday morning and said the car was being towed back in, but he some how found a sensor and replaced it, his son drove is briefly when it died and would not restart. we tried it when it got here and tried to start and yes would not start, john right away disconnected the MAF Sensor and it started not problem ??? very confusing

Is the coil wire interfering?

No John thought that as well before so he checked that and we both went out and just rechecked it and no it is not interfering, Heres another little thing we noticed when we were out there,
with the MAF Sensor unplugged and have running if barely touch the plug to the sensor it will quit

Id be then checking the connector on both ends.

I spoke to John and he told me that in his testing he checked the wires in the connector for continuity and ground and both where good, unless there is a wire in the harness that is corroded and is still sending a good signal.
They also had the Coil wire right off to inspect it.

If wiring and voltages are good then its got to be a bad part

I've seen bad ox sensors do this.