Original AMM lasted about 17 years and 209,000 miles and replaced it with one from FCP.

That one from FCP lasted about 1 year and 14,000 miles. Lucky for me, FCP took it back and replaced it with another - no charge.

Now 2 months and 3,300 miles later, the replacement has failed.

This car is not abused or driven hard. Never been crashed. Wires internal to the AMM have not been touched. No oily residue inside the hoses or on the AMM.
All the replacement parts have been Bosch and the car is stock.

What could cause 2 AMM failures in just over a year?
Something wrong with the car or just poor quality parts?
Although the parts were Bosch, I'm wondering if they were reman. or just junk.

Also the jumper wire for the diagnostic box under the hood is getting a frayed end. Could that do it?

Anyone have any ideas?
Thanks

P.S. Since this is my daughter's car and it sees quite a few miles per month, this is getting serious. The wife says "that's it, we're getting rid of that car." Help!
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"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig

I remember having to replace the jumper wire on my old turbo. Not fun but do-able. I also used slightly heaver gauge wire.

The AMM error probably is not caused by a bad connection in the jumper wire, but I could see the blinking lights being somewhat messed up.

A bad AMM would result in very poor performance. Yes, those parts are probably not made to OEM standard, but I would contact Tasca and get one in a Volvo wrapper. Or just find one in a pick&pull...

Ouch, I just looked at the prices!! Tasca wants $181 and $145 from FCP.

Check the wiring connector!! There was a TSB to use a zip tie to hold the wire in a secure place so the connection at the plug would not fray.

How do you know the AMM is dead?
What is it that fails with the AMM?
I wonder if there's a fault with the connector, or a local ground connection perhaps?


Merry Xmas

Bill

I had a 1-2-1 code leading me to believe the problem is with the sensor.
But your point is well taken and that's what I'm struggling with.
I can't believe that 2 AMMs would go in such a short time frame.

Going to look more closely at the connector, but I don't remember it ever looking damaged from the outside. May have to pull off the boot and see what's under there. Maybe some corrosion.


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"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig

Hi Again ____,

What symptoms does the car have other than throwing a 1-2-1 code?
I looked at the MAF wiring and there's only 4 wires, three to the ECU and the
Hot (+) is to a junction 23/11 that includes the injectors.
The Hot (+) is switched by that infamous Main Fuel Relay 2/32 above the radiator
on the drivers side. Here's one scenerio, Maybe the relay is chattering enough to throw a code? Maybe the ratty operation is that SOB? Something easy to check.

It wouldn't hurt to service the ground points for the ECU regarding Fuel injection in particular, There's one on the intake manifold that can go sour and murder performance. I'm guessing the worst failure is when the ground path gets resistive and throws a curve ball at the ECU, and not an outright failure.

Get some dielectric silicone and use it on your connecters, It's designed for that
to retard corrosion, salt spray etc.

Good luck, Bill

First time (the original factory AMM) it failed on the highway. Got it restarted but stalled repeatedly until we could get it off the highway. The OBD I gave a 1-2-1 code. Did the tests listed here (http://easyautodiagnostics.com/Volvo-MA ... est-g.html) to determine it was an AMM failure, so I changed it and everything was well again.

Second time (2 months ago) it stalled while sitting on an exit ramp. Got it restarted and made it home. Took it out the next day and it would stall intermittently while at idle. Triggered a 1-2-1 code. Unplugged the AMM and it appeared better, but not right. I changed the AMM and everything was fine again.

Yesterday a few minutes after the first start it was intermittent rough running and stalling when warming up in the driveway followed shortly thereafter with a 1-2-1 code. Didn't drive it after that for fear of getting stranded.

I guess that with the 1-2-1 code I'm just assuming it is the AMM again and since I'm pressed for time and have to have the car on the road again Saturday so I'm ready to just throw that part at it again (which goes against my "diagnose first" mantra). I know better and will have to try to do some diagnosis per the above tests before company gets here.

Thank you for the ideas.
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"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig

The next time that the car is running ragged, see if you measure +14 Volts
on Pin 3 of the AMM connector (A green wire)
Put your meter ground (-) on the intake manifold.

If you don't get a good reading the AMM can't work.

The MAF and the injectors are both enabled by the main fuel relay.

Relays crap out with enough cycles, but first they might get intermittent.

The 1-2-1 code might be misleading if you just think MAF.

Try spraying just the connector (not the AMM) with CRC electrical cleaner. That helped on my 240.

How are the pins on the connector? Are they all straight and solid? The AMM won't get the right signal unless the connector is in good shape and the connection is secure.