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Multiple faulty IAC sensors

J

John A Erdy

Guest
"I have a Problem with my IAT

"I have a Problem with my IAT or MAT Sensor. Part # 805223T. This is on a 2000 Merc. 5.7 L EFI. I've had my Marina Scan the engine for the defective code twice. Each time they said replace the IAT Sensor. With each new sensor lasting only 15 to 20 hours. This problem starts out as intermittent, and progresses to non stop horn in a short amount of time. The second time they removed the new sensor from the port engine and put it in the starboard engine and the horn followed the sensor. There is no performance loss when warning horn sounds. But the horn is unbearable.
At $85 a scan and $35 a sensor I need someone who knows what is going on. I have checked the bad Sensor on the water with an Ohm Meter. Only to have intermittent Continuity or Resistance on the sensor’s 2 prong plug end. Same out come on the thermometer end in the cage. I brought the sensor home and now it appears to be working fine. With the meter attached to the plug end and Hot or cold air on the thermometer end. It now changes the resistance reading consistently. Hot = lower reading. Cold = higher reading.
Is anyone else having this problem? I have ordered another new sensor (#3) this week. It reads the same as the old sensor on the Ohm meter. Mercury told my marina service center, they have not had any problems with these sensors. Any help greatly appreciated
Sincerely
John A. Erdy"
 
Sounds like inept service cent

Sounds like inept service center tech. Examine the wiring particularly the plug to the sensor. You may need a new pigtail for the sensor.
 
"John
Guy could have a good p

"John
Guy could have a good point here, if it is confirmed that your sensors are failing you need to find out the reason why, go around your wiring harness and check all the connectors for corosion, check all your grounding points as well.
Cheers
Peter C"
 
"agree with guy, sounds like p

"agree with guy, sounds like posible connector failor. also are you running the oilable filter media spark arestor (K&N Marine or some of the others on the market)? GM has a bulliton out about damage and contamination to sensor on the cars, and since its a GM sensor i would assume the same applies here......... but thats coming from a auto tech, not a marine tech."
 
if you want the manual let me

if you want the manual let me know
these sensors are very easy to diagnosis
sounds like you need to find a new shop
 
"If the sensor had intermitten

"If the sensor had intermittent resistance when tested, it not the techs fault. Why are you guys so quick to bash the shop/tech?

Two additonal things, first, you don't need to pay $85.00 to have it scanned, you can pull codes with a 12volt LED and a paperclip. Second, go to an electronics store an get a 3.4K ohm 1/4 watt resistor. Put it in place of the sensor if/when it fails. It will simulate a intake temp of 70 degrees, and then you can go on and enjoy the day on the water with no warning horn.

Dave"
 
"heck if yoru charged 85$ just

"heck if yoru charged 85$ just buy the quick code adapter for 79$, it has the led and the paper clip built in"
 
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