My check engine light on my 1992 V6 truck comes on after about 20 minutes of driving. Engine runs strong and normal. I think I'm getting a bit worse gas mileage too. I'm gonna have a diagnostic done but was wondering if anyone had any suggestions in the meantime. Does it sound like the 02 sensor? The speedometer and mileage guage also stopped working or works periodically at about the same time time this started to happen.

-shawn

 

Any guesses will be just that, guesses. Have your codes pulled and see what they are and come back here as post them up so we can better help you out.

 

BTW, you can pull your own codes: http://www.off-road.com/toyota/tech/codes/index.html

USUALLY when the mileage goes south on an otherwise good running engine,it's the O2 sensor. How many miles on the engine? Whcih engine do you have?

In reference to the intermittent problem withthe speedo, I'd check/clean the lead connections to the transmission.

 

Humanoid & Rabbit,

Thanks! 162,000 miles on the 3.0 v6. All fluids are clean and recently changed as well as plugs. I'll go to the link you suggested. BTW, the O/D off light also begins to periodically flash on the guage cluster. All this stuff started to happen at the same time.

As far as the 02 sensor, I just noticed that I'd been running with a very dirty air filter. Does anyone think that this could lead to an 02 sensor going bad?

-shawn

 

Shawn - what kind of filter are you running? Regular OEM filter or something like a K&N? If it's the K&N type filter it may have fouled up your mass air flow sensor or the air flow meter in your case.

 

Sorry, my bad; you said which engine in your original post! Clogged filter could account for the poor mileage, but I doubt very seriously it would do anything to the O2 sensor. Again, I would check all the connections to the tranny, since that's where it sounds like all your problems are originating. Have you checked the fluid? When was it last changed?

I'd stick with OEM filter; the difference in flow between that and K&N style is negligible, but they trap much smaller particals and thus are better for your engine. Go to: http://www.bobistheoilguy.com and follow the link to filters. It's a real eye opener. It's a great site overall.

Here is another INCREDIBLY valuable link to the FSM for a 1993 truck (not much difference): http://personal.utulsa.edu/~nathan-buchanan/93fsm/


In order to diagnose further, you need to pull the codes. Let us know what you find out!

 

You can pull O/D Off codes (transmission codes) just like a CEL code (engine code). Jumper the E1 and Te1 pins and turn the key to ON. Be sure to press the O/D switch on the shifter to ON.

Mike in AR

 

not sure if CEL will come one because of leaking gas cap or not......
other wise, the code should tell you something. Maybe bad alternator also....this happened to me before.

 

thanks guys for all the info. I jumpered the Te1 and Te diagnostic terminals and pulled a 42 code. When I looked it up, it shows speed sensor circuit. I figure that this is the issue since the speedo is gone bad. The speedo worked occasionally at times before it completely went out, so I don't think that it could be a broken speedo cable.

I also read in someone elses post that the O/D off light will flash when the speedo cable is broke. Does this also happen when a speed sensor circuit goes bad? Where can I locate te speed sensor? Tough or expensive to replace?

BTW - Tranny fluid and filter changed with synthetic about 6 months ago. And I'm just running a stock air filter.

-thanks for the help everyone