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740 1991 740. CODE 4-1-3. Looking for greenbook info/help

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
UPDATE I fixed it with a new EGR temperature sensor! I just had another one fail and throw the same code. Measure the resistance of the sensor. It should be approx 500 ohms. If it's open or has a huge resistance value, the sensor is bad. You can use either the one built into the valve, or the one in the pipe, they both work interchangeably.


_____-------+++++++++++++++++++++++++++++++++(++++++

I just bought a 1991 740. I noticed, after the purchase, that the check engine light bulb has been removed. No wonder he balked when I was asking if it had passed smog. So I swapped bulbs, and guess what, check engine light was on and came back first start of the engine after clearing it.

It has a code 4-1-3 stored for EGR temp sensor absent of faulty.

I have looked at the Volvo wiring diagrams.com website and I'm not finding the specs for the sensor. I'm going to do basic diag, but looking for help finding the specs for the sensor. I plan to activate the EGR valve manually and seeing what the readings on the sensor are during flow.

I wouldn't be surprised if this car has the wrong computer in it.
 
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I'm not sure if it's the same, but Bentley has the specs for the 240 EGR w/ EZK116

pg 253-6 EGR vacuum booster 85 +/-10 ohms
Temp sensor at ambient 500-1000 ohms

[And I think the EZK code is 4-3-1]
 
If ECU catches it immediately after start it's probably because of the connection failure, broken wire, etc.
If you get any kind of Ohm readings and apply vacuum on the running motor the resistance will drop very fast as long as there is EGR flow.
 
If ECU catches it immediately after start it's probably because of the connection failure, broken wire, etc.
If you get any kind of Ohm readings and apply vacuum on the running motor the resistance will drop very fast as long as there is EGR flow.

Yep. I'm over thinking it. It triggered so fast it's gotta be the wrong EZK unit or a complete open.
 
I will look at the EZK. I want EGR to stay functioning. The car needs to pass smog tests. I just passed the sniffer. I can neither confirm or deny if a third of a tank of E85 was used. Emissions numbers were low!

I can check, but is it disabled if there's the CEL?

Thinking about it, the wrong EZK box (a non EGR one) wouldn't throw a EGR code. The code was only on the EZK pin 6 socket. To that means I need to shake down the problem.

I need a wiring diagram...
 
Thanks for the spoon feed. I'm spoiled at the shop and just get to punch in the VIN and have every bit of info I need on a car such as wiring diagrams, specs, and description/operation of every system.

I made sure it was plugged it this weekend and that's still as far as I have made it. I plan to measure across the two terminals and see what kind of resistance it has, or if it's open. Then manually activate EGR and measure it's output during EGR flow.
 
5v measured between a disconnected body side harness and OPEN circuit between the two terminals for the temp sensor. Needs a sensor!
 
Just make sure you get the correct sensor. NTC vs. PTC, and the correct one for the tube that's in there.

I've seen a few that were just a broken wire. Give it the old wiggle test.
 
Search noob!

Thanks. I actually did a search and found a post by you mentioning the resistance should be about 500-600 ohms. I didn't see any broken wiring, but it may be open internally.


Got a new fuel cap gasket, fixed a evap hose, a check engine bulb, and a junkyard EGR temp sensor should get me thru smog! Thanks for the help peeps.



Update.########

I measured open circuit across the terminals for the sensor. A new sensor fixed it.
 
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