What does "HEGO" stand for?

04-05-2001, 10:27 PM

I did a self test on my '89 gt vert today, and I got a "91" code, which translates to "No HEGO switching detected" according to Chilton's. Anybody have this problem? Where is it and how do I fix it? I'm guessing it's
H***-Exhaust-Gas-O*** but if anyone could tell me I'd appreciate it.

BTW: I also got a code "31" related to the EGR valve system ("PFE, EVP, EVR circuit below min. voltage"), and either got another "91" or a "19" during the engine running test(related to HEGO or EGR respectively-Im gonna try it again tomorrow) if that helps you guys any. thanks again

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[This message has been edited by Big&bad89rag (edited 04-05-2001).]

Godslayer · 04-05-2001, 11:27 PM

HEGO stands for Heated Exhaust Gas Oxygen Sensor. If the computer says it doesn't detect switch the sensor is probably shot. Check the wiring and make sure it's ok. Then pull it out and replace it. You can test them if you have a digital voltmeter. Jack into the harness and watch the voltage, it should fluctuate quickly, if it doesn't change the sensor is bad. If the EGR is bad it will make the car buck and run poorly, basically, you would notice. The code is probably from the EVP sensor on the EGR valve. The EGR Valve Position tells the computer where the valve is. The valve is not controlled by the computer, so fixing this code can be done at your liesure.

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87 GT
Full exhaust, K&N, KB Subs, BBK STB, homeade dumps...

87 Taurus
New York
Winters Bite!

04-06-2001, 05:01 PM

thanks a lot for your help, I had a feeling my O2 sensor was going bad, (poor mileage etc.) but I didnt know that was the technical term for it. Thanks again.

nathan

04-05-2001, 10:27 PM	#1
Big&bad89rag Guest Posts: n/a	What does "HEGO" stand for? I did a self test on my '89 gt vert today, and I got a "91" code, which translates to "No HEGO switching detected" according to Chilton's. Anybody have this problem? Where is it and how do I fix it? I'm guessing it's H*-Exhaust-Gas-O* but if anyone could tell me I'd appreciate it. BTW: I also got a code "31" related to the EGR valve system ("PFE, EVP, EVR circuit below min. voltage"), and either got another "91" or a "19" during the engine running test(related to HEGO or EGR respectively-Im gonna try it again tomorrow) if that helps you guys any. thanks again ------------------ [This message has been edited by Big&bad89rag (edited 04-05-2001).]

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04-05-2001, 11:27 PM	#2
Godslayer Registered Member Join Date: Mar 1999 Location: Largo, FL USA Posts: 274	HEGO stands for Heated Exhaust Gas Oxygen Sensor. If the computer says it doesn't detect switch the sensor is probably shot. Check the wiring and make sure it's ok. Then pull it out and replace it. You can test them if you have a digital voltmeter. Jack into the harness and watch the voltage, it should fluctuate quickly, if it doesn't change the sensor is bad. If the EGR is bad it will make the car buck and run poorly, basically, you would notice. The code is probably from the EVP sensor on the EGR valve. The EGR Valve Position tells the computer where the valve is. The valve is not controlled by the computer, so fixing this code can be done at your liesure. ------------------ 87 GT Full exhaust, K&N, KB Subs, BBK STB, homeade dumps... 87 Taurus New York Winters Bite!

04-06-2001, 05:01 PM	#3
Big&bad89rag Guest Posts: n/a	thanks a lot for your help, I had a feeling my O2 sensor was going bad, (poor mileage etc.) but I didnt know that was the technical term for it. Thanks again. nathan