Question about Mazda MPV
What code did your mechanic pull from the cars computer? If it was a cat inefficiency code that usualy means the cat is going bad. If it is a sensor 2 high voltage or rich limit than it could be either. If its sensor 2 slow to respond it might be either.
If you could post the specific code/codes that would help a lot to answer your question.
Posted on Oct 08, 2010
Yes. the cat converter codes are normally po420 or po430. o2 sensor codes vary greatly but the main one are po171 or po172[engine running lean or rich]. their are a few other codes for the heater circuits in the o2 sensors also.
Posted on Oct 08, 2010
Yes, I would say that on an OBD-II system on a car 1996 and up it should be able to detect which Oxygen sensor is faulty or giving a false signal, or with a little bit of diagnostic time determine if the catalytic converter is plugged or not functioning using a sniffer.
Posted on Oct 08, 2010
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Posted on Jan 02, 2017
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May 23, 2011 | 2003 Ford Ranger Regular Cab
From this website:
http://www.obd-codes.com/p0140
P0140 - 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
What does that mean?
The Powertrain control module (PCM) will provide a .45 volt reference voltage to the Oxygen sensor. When the O2 sensor reaches operating temperature, it will generate a voltage that will vary depending on the oxygen content of the exhaust. Lean exhaust generates a low voltage (less than .45V) and rich exhaust generates a high voltage (greater than .45V). O2 sensors on a specific bank marked as "sensor 2" (as this one is) are used to monitor emissions. A Three-Way Catalyst (TWC) system (catalytic converter) is used to control tailpipe emissions. The PCM uses the signal received from Oxygen sensor 2 (#2 indicates aft of catalytic converter, #1 indicates pre-converter) to read efficiency of TWC. Normally this sensor will switch between high and low voltage at a noticeably slower rate than the front sensor. This is normal. If the signal received from rear (#2) O2 sensor indicates that the voltage has "stuck" between .425V to .474 V, the PCM determines this sensor is inactive and this code will set.
Potential Symptoms
Your check engine light(CEL), or malfuction indicator lamp (MIL) will be illuminated. There will not likely be any noticeable drivability problems other than the MIL. The reason is this: The rear or post catalytic converter Oxygen sensor does not affect fuel deliver(this is an exception on Chryslers). It only MONITORS the efficiency of the catalytic converter. For this reason, you will likely not notice any engine trouble.
Causes
The causes for a P0140 code are fairly few. They could be any of the following:
Shorted heater circuit in O2 sensor. (Usually requires replacement of heater circuit fuse in fuse block also)
Shorted signal circuit in O2 sensor
Melting of harness connector or wiring due to contact with exhaust system
Water intrusion in harness connector or PCM connector
Bad PCM
Possible Solutions
This is a fairly specific problem and shouldn't be too difficult to diagnose.
First, start engine and warm up. Using a scan tool, watch the Bank 1, sensor 2, o2 sensor voltage. Normally the voltage should switch slowly above and below .45 volts. If it does, the problem is likely intermittent. You'll have to wait for the problem to surface before you can accurately diagnose.
However, if it doesn
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first check for vacuum leaks, broken vacuum elbows, hoses, gaskets, etc
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