What does this mean? My truck has been idling poorly recently and I just did the paperclip diagnostic to find this code and a code 071. I know what 071 is, but I haven't ever seen an 021. I looked in my FSM and couldn't find anything. Help. Thanks.
Code 021
- Thread starter Rogue
- Start date
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A 21 is number 1 O2 sensor.
My O2 sensor was bad. I forgot if it was #1 or #2
I would reset the light over and over till it stayed on after resetting the computer.
Yes it could make you motor run bad. Mine didn't run bad and it ran no better onec I replaced them.
You may as well replace them both. Its cheaper for both of them from Cdan.
We have 2 O2 sensors so one might compensate for the other if its bad or going bad.
Check to see if they have been replaced from the recall. If not, its FREE other wise it will hurt your credit card. But not to bad.
I would reset the light over and over till it stayed on after resetting the computer.
Yes it could make you motor run bad. Mine didn't run bad and it ran no better onec I replaced them.
You may as well replace them both. Its cheaper for both of them from Cdan.
We have 2 O2 sensors so one might compensate for the other if its bad or going bad.
Check to see if they have been replaced from the recall. If not, its FREE other wise it will hurt your credit card. But not to bad.
- Thread starter
- #5
I ordered the parts a bit ago and will see them sometime next week. The recall work was done early in the trucks life, so no deal there. Until the new parts get here and my idle hopefully fixes itself, I will be grateful that I installed a hand throttle a year ago that I can use to help control the idle.
semlin
curmudgeon
Rogue, code 71 is a bad egr temp sensor signal on a 94. I think a bad egr system could trigger the 02 sensor signal if the EGr problem is affecting your mixture?
code 71 means either the sensor is busted or the EGR pipe is not the right temperature which means the system is not functioning. I believe the sensor does nothing but tell you if the EGR system is working or not so I'd focus on the EGR., Start with checking the modulator by popping the lid and checking the filter and then the condition of all the vacuum hoses and cleaning out the little metal tubes, especially the ones that go into the throttle body and the one that passes through the intake plenum, then remove the EGR valve and throttle body and clean out the tube in the intake plenum between the EGR and the throttle, then replace the VSV then replace the EGR valve.
code 71 means either the sensor is busted or the EGR pipe is not the right temperature which means the system is not functioning. I believe the sensor does nothing but tell you if the EGR system is working or not so I'd focus on the EGR., Start with checking the modulator by popping the lid and checking the filter and then the condition of all the vacuum hoses and cleaning out the little metal tubes, especially the ones that go into the throttle body and the one that passes through the intake plenum, then remove the EGR valve and throttle body and clean out the tube in the intake plenum between the EGR and the throttle, then replace the VSV then replace the EGR valve.
71 is for all EGR system; EGR: hose,valve,temp sensor and circuit,VSV for EGR and and circuit, and ECM pre the FSM
They forgot to add the modulator. A bad modulator can fry all the above trouble areas.
They forgot to add the modulator. A bad modulator can fry all the above trouble areas.
semlin
curmudgeon
Kurt, I believe only the EGR temp sensor signal can trigger the code 71 on a 93 or 94. It explains this in the earlier FSMs. There is no other sensor in the EGR system. I know this because my non-California 1993 has no temp sensor and never threw a code even though the entire EGR system was blocked and the VSV was bad.
The 94 FSM says code 71. Trouble areas, valve hose gas temp sensor or circuit, VSV and ECM.
I don't know what the 93 says but they should be close to the same.
I don't know what the 93 says but they should be close to the same.
semlin
curmudgeon
"trouble areas" indicates where to look to fix the code and lists every part of the EGR system, but under "diagnosis" for code 71 all it says is "EGR gas temp below predeterined level during EGR operation". This is what actually triggers the code.
I don't have a 93 FSM either (I got the 94 FSM for the lockers) but in the 91 FSM there is an asterix beside code 71 and down at the bottom it says "California vehicles only".
I don't have a 93 FSM either (I got the 94 FSM for the lockers) but in the 91 FSM there is an asterix beside code 71 and down at the bottom it says "California vehicles only".
I and others may of taken that their temp sensor is bad and replace it.
The temp sensor is still good when one of the other EGR parts are bad.
I just wanted to point out where to look for the bad part.
On the 94 93 system I think I under stand how the temp sensor works.
If when the EGR valve is suspose to be open but its not, the temp will read cold as hot gas is not passing the sensor.
If the valve is stuck open then the motor will run rough at idel, right? If so then if you have bad idel, the EGR valve may be stuck open.
As for JUNK, he needs to get a diesel motor for his 80
Wait new diesels motors will have EGR system on them in the not to far future, if not already.
The temp sensor is still good when one of the other EGR parts are bad.
I just wanted to point out where to look for the bad part.
On the 94 93 system I think I under stand how the temp sensor works.
If when the EGR valve is suspose to be open but its not, the temp will read cold as hot gas is not passing the sensor.
If the valve is stuck open then the motor will run rough at idel, right? If so then if you have bad idel, the EGR valve may be stuck open.
As for JUNK, he needs to get a diesel motor for his 80
Wait new diesels motors will have EGR system on them in the not to far future, if not already.
