My brother's SC just threw a Check Engine Light.

~1995 SC300
~OBD1

I had a friend find the code using the "two pin in the plug" method. If anyone knows of this method can you post specific details on how to go about using this method. I was not there when this was done so I missed the entire show.

Anyway, the code is 71.
~What is its definition?

~What can I do to fix it?

Thanks!

 

Code 71 is EGR malfunction. I have that same code on my 95 SC300. I believe you have to replace the EGR sensors in order for it to be fixed. I drive it and it comes on and off. I haven't fixed it yet.

 

71 EGR System Malfunction


Diagnosis

* EGR gas temp below predetermined level during EGR operation.
* Open circuit in EGR gas temp sensor signal (THG).

Trouble Area

* EGR system (EGR valve, EGR hose etc.)
* EGR gas temp sensor circuit
* EGR gas temp sensor
* VSV for EGR circuit
* VSV for EGR
* ECU

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I found this information above here:
http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

I found it extremely helpful. I even tells me how to do the old "two pin in the plug" method to determine a code. SOOOOO, now we are getting somewhere. I will go ahead and inspect the system. Has anyone repaired this themselves and how did you go about doing it?

 

Thank you much. The CEL used to be a soft CEL so it would come on and off every time we hit the gas. But lately it has just remained on.

~How much did you get the sensor for?

~Where is it located?

~Where did you buy it?

 

I did not buy a new sensor. It is located closely near the firewall around the throttle body area. I am sure you can just remove it and get a EGR block off plate and wire in a resistor to get the check engine light off. There are some threads that explain how to replace the EGR on Supraforums.

 

I'd rather not. I live in Cali where that sort of stuff is illegal. But thanks for your help.

 

Edit:

i would recommend checking the vacuum lines to the solenoid first that would be an easier thing to check.


i would remove the temp sensor and clean it off, carbon will build up after awhile and will not allow the temp sensor to read correctly which in turn sets off the check engine light. you can use brake clean, gas ect... to dissolve the carbon off the sensor

 

My GS300 threw code 71 years ago exactly as the OP described. It would come on briefly and then go away. My brother cleaned the EGR thoroughly and the problem went away for a while and then came back. The cause ended up being the vacuum modulator, which I believe is about a $60 part. Fixed and done. It is quite common with the I-6, non-VVTI engines.

 

I LOVE the search button My 92 SC 300 just started throwing this code the other day! It came on then went off, now it is constant. Always the same code (71). We are going to check the lines and go from there.

Thanks for posting up about your issue JspecSC3

 

like the others said, code 71 is EGR malfunction.

it can be several things including:
- egr valve sticking
apply vacuum directly to valve, engine should run rough or die (if not, clean w carb cleaner)

- vacuum modulator diaphagm torn (the problem in my case - replace)

- vsv resistance too high
if not within 38.5 to 44.5 ohms at 67F or 20C replace

- egr temperature sensor,
resistance specs at 50°C (112°F): 64 - 97 k ohms At 100°C (212°F): 11 - 16 k ohms At 150°C (302°F): 2 - 4 k ohms.. if not within range, replace the sensor


if none of those are bad, the problem may lie in the wiring to the vsv or the temperature sensor. it most likely will be the modulator or the vsv.

the specs are taken from alldatadiy.com

 

Very useful info!

 

im getting the same code 71. i took pics of the egr system so can somebody help me and tell me which one i need to clean or replace. oh and also if anybody knows if a leaky hose would be the problem. i replace one of the hoses becuz it was so brittle that it had a crack and it looks like mostly all of them are the sameway.

 

another pic

 

and another one

 

and the last one