Code 136-could this be the cause?

[scott.475]

Hey all, I took advantage of a good sale on an Auto Xray 5000 and hooked it up to my 94 4.0 tonight. It gave me a code 136 (check engine light has been on for a while). I think it said something about the O2 sensor not being hot enought "bank 2" or "left", but while playing with the new toy, I cleared out the message. Awhile back, while reinstalling my transmission, I smashed the plastic coupling for the driver's side O2 sensor...smashed real good, as a matter of fact. I was able to get both ends back together, but it didn't look real good. I am figuring this is the cause of the problem, but I'm wondering if y'all might have any other possible ideas?

Unfortunatley, I didn't smash the sensor side of the plug, but rather the side that runs into the computer...

 

[dogfriend]

Actually, my Ford EEC IV book says:

Code 136 (Engine Running) Definition: HEGO (HO2S-2) sensor circuit indicates always lean.

This could be due to the damaged connector, or may be due to a different problem such as a vacuum leak that is causing the mixture to always be lean.

I would advise to repair the damaged connector first. You may be able to get the connector from a salvage yard - especially if you can find an Explorer or Ranger in a Pick and Pull yard.

 

[scott.475]

dogfriend,

Thanks. What manual are you using, and where did you find it? Does it give possible fixes for the given codes?

-Scott

 

[dogfriend]

I have this book:

http://www.amazon.com/gp/reader/0837603013/ref=sib_dp_pt/104-2704176-1385525

You might be able to find it at the library or buy it from Amazon. I bought it a long time ago, so I don't remember where I got it from. It is a very good book.

 

[scott.475]

Okay, thanks. I scanned it again today and think the EEC just isn't picking up the sensor with the smashed plug. The message on the scanner says "136 Lack of Heated Oxygen Sensor switch during KOER indicates lean bank 2" I take the word "lack" to mean it just is not getting picked up, I think "bank 2" simply indicates left side.

 

[dogfriend]

Lack of switch means that the PCM isn't seeing the O2 sensor signal or the signal isn't "switching".

What is meant by "switching" is that the O2 sensor generates a voltage based on the amount of oxygen it sees in the exhaust stream. When the mixture is "perfect" the O2 sensor should read approx .4 Volts. The PCM uses the O2 signal to adjust the mixture. When the O2 sensor is working correctly, it will "switch" from reading less than .4V to more than. 4V as the PCM attempts to correct the mixture. It is supposed to switch back and forth, always trying to get the perfect mixture but never actually succeeding (for very long).

What the code is telling you is that the PCM is not seeing the switching that it expects to see. I think that it is very likely that the voltage is wrong because of the damage to the connector, so I would try to fix that first to see if that is the problem.