First, off first post so go easy on me.

Second, 88 pickup/ 22re, no major mods.

I've been researching how to get the codes for the cel. Jumpered term T to
E1 and got code 21 and 51

21 is o2 sensor. Followed it back to a plug under the driver's seat. It is a four wire sensor. Wire colors: white, blue, and two blacks. The two blacks ohm out at 11.8 ohms. White and blue are open to each other, ground and any combo i try. do i have a bad sensor?

FYI I also have a pretty good crack in my header right after all four
exshast(?) come together. could this be affecting the reading the sensor is getting?

Sorry if this is a bit long, just trying to get all the facts out there.

Any help would be great, thanks in advance.

 

the exhaust leak can cause the O2 sensor to read incorrectly.
the resistance between black wires sounds okay (they are the heater circuit in the O2 sensor)
you would not be conductive between blue and white unless the sensor was fully warmed up.
You can check it with a digital multimeter with the engine running and check the voltage between the blue and white wires. It should fluctuate between approx .2 and .7 volts with the engine running.

 

Thanks, you put my mind to rest. now i just have to find a new header and muffler, might just replace the whole sha-banga-bang.

You know anything about the code 51? found this on Off-road.com/toyota/tech/codes

SWITCH SIGNALS
IDL (tps) CONTACTS OFF, NEUTRAL START SWITCH OFF, A/C SWITCH "ON" SIGNAL TO ECU

WITH DIAGNOSTIC CHECK CONNECTOR SHORTED

--A/C SWITCH/CIRCUIT

--A/C AMPLIFIER

--TPS/CIRCUIT

--NEUTRAL START SWITCH/CIRCUIT

--ECU

 

Means that when the jumper is inserted and the ignition key is turned to "on", either the TPS IDL/E2 contacts are not signalling the throttle is closed (but it should be if your foot is not on the gas pedal), the air conditioner switch is turned on, or the clutch pedal is depressed (or the switch is activated)... or a combination of the above, or there is a problem with the associated wiring (to the switches mentioned above) or the ECU is faulty.

Why?

 

o.k. so that pretty much leaves, the clutch switch, throttle, air conditioner, or anthing in between. j/k Thanks for the help.

btw the o2 sensor read .5 with the motor running so i'm gonna call it good and get a new exhaust

 

well, the signal should bounce, not be constant. The ECU uses it to say "rich" or "lean" not how rich or lean so... a constant .5 may mean the O2 is fouled.