BriMcc

I just replaced my main o2 sensors on my 92 SC4 (code 25). My check engine and trac light still are on after disconnecting and reconnecting the battery! Help!!

VQT

Did you check to see if the main O2 were the problem?

There is a lot more to this test that I can’t type in because it involve looking up different page of the manual. It is recommend that you buy the book. Then when you don’t understanding what the book read ask forum member. Hopefully someone with knowledge will try to answer it. I am not a mechanic. I just read drom the book and troubleshoot the problem myself.

DIAG. TROUBLE CODE 25/26 FOR 93 SC400

There is a DLC1 under the hood. It’s a small black box with a cap covered located at the front left of the engine.
1. Warm up the engine to normal operating temperature
2. Connect terminal TE1 and E1 with a paper clip.
3. With a voltmeter, connect positive probe to terminal VF1, VF2 and negative probe to terminal E1 of the DLC1. Probe VF1 and E1 then VF2 and E1.
4. Warm up the oxygen sensor by running engine at 2,500 rpm for about 2 minutes.
5. Then, maintain engine at 2,500 rpm, count how many times needle of volt meter fluctuates between 0 and 5 V.
Results
Needle fluctuates 8 times OK
Continue at 0 V NG type I
Continue at 5V NG type II

Check Voltage between terminals OX1, OX2 and E1 of DLC1.

NG type I
1. Engine still at normal operating temperature.
2. Measure voltage between terminal OX1, OX2 and E1 of DLC1 when engine suddenly race to full throttle.
3. The voltage should be 0.5 V or higher at least once----OK
Need to perform this inspection within 1 sec.

NG type II

There are too much in formation to type in here. Need the whole repair manual.

There is another check for oxygen sensor

1. Start engine and warm up
2. After engine is warm up, let it idle for 3 min.
3. With A/C ON and trans. In D position (O/D ON) perform gradual acceleration within the range 1,300-1,700 rpm (centered around 1,500 rpm)
(Take care that the engine speed does not fall below 1,200 rpm when shifting. Gradually depress the accelerator pedal and kept it steady so that engine breaking does not occur.)
4. Maintain the vehicle speed at 40-50 mph (64-80 km/h)
5. keep the vehicle running for 1-2 min. after starting acceration.

HINT: If a malfunction exists, the malfunction indicator lamp will light up after approximately 60 sec. from start of acceleration.

NOTICE: If the conditions in this test are not strictly follow. Detection of malfunction will not be possible.

BriMcc

Sounds like a major amount of work. I would take it to a Lexus dealer but there is nothing in my town. If I travel to a dealer what can I expect to pay of the trouble shooting. Its cost me over $300 Canadian so far. Is there any harm in leaving it as is other then I don't have trac control for the Canadian winters!

VQT

Check all the connection. did you put the vacunm line back from the throttle body. There is may be some wires you did not plug back.

Order the repair manual and follow the instruction. You'll save a lot on this work. It's looks hard at first but it's not that difficult. Read my copy of the trouble shoot carefully and follow it while you are waiting for your own manual.
does the car idle smoothly? code 25 could also mean your TPS or MAF sensors is faulty. That's why you need to check it out before replace thing people suggested.

Good Luck

SupraCoup3

a temporary fix for this problem is to pull the EFI fuse in the fuse box located in the hood.

It's the second one in from the left -- it's the only 30 Amp fuse I believe.