woody

I am getting a DTC 144 on a 2.3 4 cyl. 1996 ranger 5 speed. The check
engine light is on. Auto Zone read the code and reset the check engine
light but came back on. It gets 23 MPG and runs good. The following is
given for that code.

144 (M) Oxygen sensor not switching Single, Right or Rear HO2S - Fuel
control
How many sensors does it have?

I have bought a FSM wiring manual but don't have the other manual yet. What
should I check for before getting an O2 sensor, and if I replace the sensor
should it be from the dealer or another brand. I have read negative
comments about Bosch sensors. TIA

jim warman

For some reason, P0144 doesn't show in the factory PC/ED manual... but it is
a generic OBD codes signifying the sensor isn't switching and the voltage is
high. There are very few things that will drive the mixture rich (compared
to the number of things that will drive the mixture lean)... Interesting
that the OBD definition is bank 1 sensor 3.... (where yours should only have
two sensors).

I think I'd look for a second opinion before recommending any repair
attempts.

tango

Thanks Jim, I am aware that this is not definitive and I will not replace
anything until I get some more info.
The truck has 104,000 miles and runs good so it would not be a big deal to
replace the oxygen sensor if I can't narrow it down. I will wait until I
pick up a FSM on ebay as it is not critical at this juncture.

woody

I found the problem today. I heard what sounded like a small exhaust leak
and took the truck to a muffler shop and the catalytic converter has a
small leak which would explain the code for an oxygen sensor.
I was given a price of 198.00 plus tax for a new converter with a 5 year
50,00 mile warranty.
My question is how do I determine what brand, is a good replacement
converter as I know little about catalytic converters.
Is there any special lubricant or tool used to remove the oxygen sensor. I
will not attempt this job but would like to know about any potential
problems before I have it done.

PO144 is an O2 sensor lean running code. This would be a front (pre
converter) sensor as the rear one is a catalyst efficiency code.
You really need a scanner to troubleshoot it effectively (watch the
sensor voltage and richen artificially with propane or acetelene and
see if the sensor "clocks") but most likely you do have a bad sensor.
Dealer likely the best bet, but anything other than a Bosch is likely
OK. I'm not a fan of Bosch, from experience.

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