jrhone

I have a 92 sc400 and the check engine light is on. The code is 25, which I think means the oxygen sensor. Can someone confirm this code and let me know what this will cost and if it is something I can repair myself. I would appreciate it!

VQT

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.

Good Luck and let us know the results.

jrhone

Ok, we have determined that the oxygen sensors are fine. What else could it be? Thanks.

VQT

jrhone,

Did you follow my replied before taking you car to the dealer? If you didn't check the way I type up or did not read the post and brought the car to the dealer. What can I say about the dealer charge so much money to fix your car...