93 4runner 3.0 with CEL 21
12-10-2011, 09:35 AM
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93 4runner 3.0 with CEL 21
I have a 93 4runner with 216k miles and a 3.0. threw CEL 21 the other day and is not starting as easy as it used to. The starting issue happened first with the CEL the next day while driving to work. Code 21 is the only code that is blinking. Is there a way to check the other codes, if any, or does it blink on code and then the next meaning 21 is the only code currently?
I used the FSM procedure for checking the o2 sensor and that led me to believe the sensor was fine but it was running too rich (voltage reading above 0 when connected to VF and E with the PCV tube disconnected. I went ahead and ordered a Denso o2 sensor from autozone so I could have it if it turned out to be the issue.
Went to loosen the bolts on the o2 sensor to find them both rounded like someone has tried and failed to pull it before. I know there are three different questions in there but feel free to pick any or all to answer.
Thanks, Jordan
I used the FSM procedure for checking the o2 sensor and that led me to believe the sensor was fine but it was running too rich (voltage reading above 0 when connected to VF and E with the PCV tube disconnected. I went ahead and ordered a Denso o2 sensor from autozone so I could have it if it turned out to be the issue.
Went to loosen the bolts on the o2 sensor to find them both rounded like someone has tried and failed to pull it before. I know there are three different questions in there but feel free to pick any or all to answer.
Thanks, Jordan
12-10-2011, 03:41 PM
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The codes read out one after the other. If you get 21, then 21 again, that's the only code.
What does CEL 21 mean? Oh, you wanted us to look it up. http://www.ncttora.com/fsm/1990-1995...e/diagnosi.pdf "Open or short in O2 sensor heater circuit." What test did you do for that? If you checked the voltage of the sensor, that won't tell you anything about the heater. Most likely you have an open in the O2 sensor itself (so replacing will cure it), but you could have an open (or short) anywhere in the circuit (so examine the connector and wiring, at least).
PB Blaster is often recommended. I'm not in the RustBelt, so I usually get by with Liquid Wrench. If the bolts are really rounded you'll need a light touch with ViseGrips to get them out. Don't break them off! You're better off getting the replacement bolts from the Dealer; hardware store replacements will be plated, and that plating will disappear a few seconds after you start the truck.
Good Luck!
What does CEL 21 mean? Oh, you wanted us to look it up. http://www.ncttora.com/fsm/1990-1995...e/diagnosi.pdf "Open or short in O2 sensor heater circuit." What test did you do for that? If you checked the voltage of the sensor, that won't tell you anything about the heater. Most likely you have an open in the O2 sensor itself (so replacing will cure it), but you could have an open (or short) anywhere in the circuit (so examine the connector and wiring, at least).
PB Blaster is often recommended. I'm not in the RustBelt, so I usually get by with Liquid Wrench. If the bolts are really rounded you'll need a light touch with ViseGrips to get them out. Don't break them off! You're better off getting the replacement bolts from the Dealer; hardware store replacements will be plated, and that plating will disappear a few seconds after you start the truck.
Good Luck!
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