How many O2 sensors does this car have? I see two offered, front and rear. I'm pretty sure I have a bad one as the car has 116,000 miles and the O2 sensor(s) has (have) never been replaced. If there are two, how do I know which one is bad.? I'm confused... Thanks
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Did you replace the front and rear or just the front? Rear brakes can make the pulsation as well. Also if your ABS system is activating that could be described as a "pulsation". The ABS problem is usually caused by a bad wheel speed sensor or ABS module failure. ABS modules can be rebuilt (see ebay BBA-Reman) Wheel speed sensors are available at most auto parts stores. Some Saabs require the replacement of the whole hub assembly.
the p0421 code on this vehicle is either caused by a bad catalytic converter or an oxygen sensor. your mechanic has a scan tool that he can verify if the converter is faulty by comparing the rear o2 sensor to the front sensor. If the rear o2 sensor's voltage is switching from rich to lean (01-1.0v) similar to the front's, then, it's a bad converter. The rear o2 sensor should keep a steady voltage reading. Have him do this test while at cruising speeds. good luck
P0131 - O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 (sensor is before the catalytic converter)
Possible causes- Front Heated Oxygen Sensor Bank 1 harness is open or shorted - Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection - Faulty Front Heated Oxygen Sensor Bank 1 - Inappropriate fuel pressure - Faulty fuel injectors - Intake air leaks may be faulty - Exhaust gas leaks P0132 - O2 Sensor Circuit High Voltage Bank 1 Sensor 1 Possible causes- Front Heated Oxygen Sensor Bank 1 harness is open or shorted - Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection - Faulty Front Heated Oxygen Sensor Bank 1 - Inappropriate fuel pressure - Faulty fuel injectors - Intake air leaks may be faulty - Exhaust gas leaks
I am not really sure what is going on here with the same O2 sensor giving these lean and rich codes, if nothing else is apparent and the engine runs well you may have a defective O2 sensor.
is that the code you get from comp is PO420 eng light if so worst news either you have an exh leak between o2 sensor 1 and o2 sensor 2 or the front o2 sensor is lazy or the front catyletic converter is not working
basicaly code is only triggerd when engine is hot and the front o2 sensor and the rear o2 sensor read the same voltage when conv is working the front o2 sensor will fluctuate rapidly from 0v to 1v and rear o2 sensor will remain steady at 0.5v
try to explain best i can plz vote comment or reply if you need more help
Make sure all your injector connectors are clean and not corroded. make sure you have the correct resistor sparkplugs. And if both of those things are okay you probably have a bad direct ignition cassette.