Engine light and warning light on.

[Chomper]

That was stupid of me. I thought it would be like hondas, by ecu. I found it and the code seems to be 21. That means its the oxygen sensor? should I just replace it? Do you know if it can cause the low idling problem, or is that something else?

thanks for your help

Originally Posted by pwpanas

No...look for the OBD diagnostic port under the dash, by the door on the driver's side. There's also another diagnostic port at the back (firewall) side of the engine bay, above the downpipe.

[pwpanas]

Originally Posted by Chomper

...the code seems to be 21. That means its the oxygen sensor? should I just replace it?...

According to the documention, the problem is either:

Open or short in heater circuit of main heated oxygen sensor (Fr) for 0.5 sec. or more.

Possible trouble areas are:

• Open or short in heater circuit of main heated oxygen sensor.
• Main heated oxygen sensor heater
• ECM

....OR....

Main heated oxygen sensor signal voltage is reduced to between 0.35V and 0.70V for 60 sec. under condition
a) ~ (d). (2 trip detection logic)

a). Engine coolant temp.: Between 80° C (176°F) and 95°C (203°F)
b). Engine speed: 1,500 rpm or more
c). Load driving (EX. A/T in overdrive (5th for M/T), A/C ON, Flat road, 50 mph <80 km/h>)
d). Main heated oxygen sensor signal voltage: Alternating above and below 0.45 V.

Possible trouble areas are:

• Main heated oxygen sensor circuit
• Main heated oxygen sensor

Simply replacing the O2 sensor might or might not fix the problem(s). In theory, the problem could also be in the wiring or the ecu itself. In other words, it's hit and miss if you start swapping parts without going through the proper troubleshooting procedures. In order to do this troubleshooting properly, you'd need a copy of the TSRMs (Toyota Supra Repair Manuals), and you'd need to follow ALL of the troubleshooting/diagnostic steps for each of the possible trouble areas listed above.

For what it's worth, if you're going to be working on your own Supra, I have to strongly recommend that you pick up your own copy of the TSRMs. They will literally pay for themselves several times over, which makes them an excellent investment.

One last observation: if your Supra has more than 100K miles on it, and especially if it has more than 150K miles on it, and your primary/main O2 sensor is the one that came with the car when it was new, I'd suggest you replace your primary O2 sensor regardless...

Originally Posted by Chomper

...Do you know if it can cause the low idling problem...

Yes, it could be responsible for low idling, due to the likely-inaccurate O2 sensor readings being passed back to the ecu in closed-loop.

[Chomper]

Yeah, I will probably replace the O2 sensor to see if thats the case. If its not, like you said, it might be time for a O2 replacement anyways. i'll do the replacement and hopefully thats the problem.

Thank you for your help.

Originally Posted by pwpanas

According to the documention, the problem is either:[/list]....OR....
[/list]Simply replacing the O2 sensor might or might not fix the problem(s). In theory, the problem could also be in the wiring or the ecu itself. In other words, it's hit and miss if you start swapping parts without going through the proper troubleshooting procedures. In order to do this troubleshooting properly, you'd need a copy of the TSRMs (Toyota Supra Repair Manuals), and you'd need to follow ALL of the troubleshooting/diagnostic steps for each of the possible trouble areas listed above.

For what it's worth, if you're going to be working on your own Supra, I have to strongly recommend that you pick up your own copy of the TSRMs. They will literally pay for themselves several times over, which makes them an excellent investment.

One last observation: if your Supra has more than 100K miles on it, and especially if it has more than 150K miles on it, and your primary/main O2 sensor is the one that came with the car when it was new, I'd suggest you replace your primary O2 sensor regardless...
Yes, it could be responsible for low idling, due to the likely-inaccurate O2 sensor readings being passed back to the ecu in closed-loop.

[supraman08]

my problem sounds very similar ,, but my engine and warning light isnt always on .. it will come on when i have been driving for a while , or somtimes when i really get into it , sometimes it doesnt come on at all , could this mean that the o2 sensor is almost stuffed ?

[pwpanas]

Originally Posted by supraman08

my problem sounds very similar ,, but my engine and warning light isnt always on .. it will come on when i have been driving for a while , or somtimes when i really get into it , sometimes it doesnt come on at all , could this mean that the o2 sensor is almost stuffed ?

Honestly, it sounds more like a boost leak. Have you checked for this?

[supraman08]

na everything has been checked out except for the o2 sensor .. the turbos and manifold and everything are all new ..

[pwpanas]

Originally Posted by supraman08

na everything has been checked out except for the o2 sensor .. the turbos and manifold and everything are all new ..

Sorry...vacuum leak then. ...and what are the engine codes stored in your ecu?