Trouble codes P0154, P0155, and P1153 have to do with your Chevy Blazer's
Oxygen Sensors. We recommend having a smog check repair station conduct a
fuel system feedback test to ensure your Chevy's oxygen sensors are working
properly.
This includes ensuring the oxygen sensors are working properly, your
Blazer's emissions computer is receiving the signals from the oxygen
sensors, the computer is computing the data properly and sending the correct
signals to the fuel injectors to either increase or decrease fuel delivery
to the combustion chambers.
The feed back test will utilize a 5-gas analyzer (usually a smog machine)
and propane. The smog technician should introduce propane to the intake
system and ensure the oxygen sensor is reading this introduction as an
increase in CO, and ordering the computer to decrease fuel delivery at the
instant propane is added to the system. This test should be done after the
engine has sufficiently warmed up and while it is running at idle. If no
change in fuel delivery is seen we know we have a feedback problem. Then the
diagnose should turn to which part of the feedback system is defective.
Using a voltmeter the technician should observe the voltage output of the
oxygen sensor as propane is added. Voltage should increase. If there is no
increase we have a defective O2 sensor. The sensor should be replaced and
the test started over. If voltage increase is present at the sensor output
the technician needs to ensure voltage increase is also present at the
computer input terminal. If voltage is present at the terminal as well next
the smog technician must ensure the computer output terminal to the fuel
injectors are lowering "injector pulse rates".
