Long story short codes read o2 sensor and oil sending light replaced both but the check engine light still on despite trying to clear codes with obd scanner

0 2 sensor near the catalytic converter or

replace the catalytic converter

The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar.

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some codes dont cause power loss or may not even notice anything wrong but a check engine light a p0152 code means following answer courtesy of OBD-CODES.com === P0152 O2 Sensor (High Voltage) OBD-II Trouble Code Technical Description Article by Dale Dale Toalston ASE Certified Technician 02 Sensor Circuit High Voltage (Bank 2 Sensor 1) What does that mean? The o2 (oxygen) sensors basically measure oxygen content in the exhaust. The PCM (powertrain control module) then uses this information to regulate fuel injector pulse. The o2 sensors are very important to proper operation of the engine. Problems with them can cause the PCM to add or take away too much fuel based on the faulty o2 sensor voltage. A P0152 code refers to the Bank 2, sensor 1, o2 sensor. (Bank 1 would contain cylinder 1 and bank 2 is the opposite bank. Bank 2 doesn't necessarily contain cylinder 2.) "Bank 2" refers to the side of the exhaust that DOES NOT contain cylinder number 1 and "Sensor 1" indicates that it is the pre-cat sensor, or forward(first) sensor on that bank. It is a four wire sensor. The PCM supplies a ground circuit and a reference voltage of about .5 volts on another circuit. Also for the o2 heater there is a battery voltage supply wire and another ground circuit for that. The o2 sensor heater allows the o2 sensor to warm up faster, thus achieving closed loop in less time than it would normally take for the exhaust to warm the sensor up to operating temperature. The O2 sensor varies the supplied reference voltage based on oxygen content in the exhaust. It is capable of varying from .1 to .9 volts, .1 indicating lean exhaust and .9 indicating rich exhaust. NOTE: A condensed explanation of fuel trims: If the o2 sensor indicates that the oxygen voltage reading is .9 volts or high, the PCM interprets this as a rich condition in the exhaust and as a result decreases the amount of fuel entering the engine by shortening injector "on time". The STFT (short term fuel trims) would reflect this change. The opposite would occur when the PCM sees a lean condition. The PCM would add fuel which would be indicated by a single digit positive STFT reading. On a normal engine the front o2 sensors switch rapidly back and forth two or three times per second and the STFT would shift positive and negative single digits to add and remove fuel to compensate at a similar rate. This little "dance" goes on to keep the air/fuel ratio at it's optimal level. Short term fuel trims or STFT reflect immediate changes in fuel injector "on-time" while long term fuel trims or LTFT reflect changes in fuel over a longer period of time. If your STFT or LTFT readings are in the positive double digits (ten or above), this indicates the fuel system has been adding an abnormal amount of fuel than is necessary to keep the proper air/fuel ratio. It may be overcompentsating for a vacuum leak or a stuck lean o2 sensor, etc. The opposite would be true if the fuel trim readings are in the negative double digits. It would indicate that the fuel system has been taking away excessive amounts of fuel, perhaps to compensate for leaking injectors or a stuck rich o2 sensor, etc. So when experiencing o2 related issues, reading your fuel trims can indicate what the PCM has been doing over the long term and short term with regard to fuel. This code indicates that the o2 sensor was stuck too high or in the rich position. The PCM monitors this voltage and if it determines that the voltage is too high out of range for too long, P0152 may set. Symptoms Symptoms may include: MIL (Malfunction Indicator Lamp) illumination Engine may run very rough Engine may be running lean or rich depending on if the o2 sensor is reading correctly or incorrectly Lack of power Increased fuel consumption Causes Potential causes of an P0152 code include: Bad bank 2, 1 o2 sensor incorrectly reading rich condition Engine running rich and o2 sensor Correctly reading rich condition Signal shorted to voltage in harness Wiring harness damage/melted due to contact with exhaust components Vacuum leak (make have lean codes (P0171, P0174) present with it) Leaking injectors Bad fuel pressure regulator Bad PCM Possible Solutions If you have any lean or rich codes associated with this code, focus on fixing these first because these can cause the o2 sensor voltage readings to appear to be faulty when they are in fact only reading correctly. So, with the engine running at operating temperature, use a scan tool to observe the Bank 2,1 o2 sensor voltage reading. Is it high? If so, look at the long term and short term fuel trim readings. The fuel trims are affected by the o2 sensors as noted above. If the LTFT reading for that bank is indicating negative double digits (PCM trying to take away fuel to compensate for problem) try inducing a vacuum leak to see if the sensor voltage then goes lean and the fuel trims increase. If the o2 sensor responds, suspect a problem with the engine, not the sensor. There may be other engine codes to help you. If the o2 sensor reading remains high (0.9 volts or above) and won't respond then shut off engine. With KOEO (Key on engine off) disconnect the o2 sensor and look for signs of corrosion or water intrustion. Repair as necessary. The voltage reading should now be about 0.5 volts. If so, replace the o2 sensor, it's shorted internally. If after unplugging the o2 sensor the voltage reading on the scan tool doesn't change, then suspect wiring problems. Inspect the harness and look for any melted wires or anywhere that the o2 sensor harness is making contact with the exhaust components. If you are unsure, you can check for continuity of all four wires between the sensor and the PCM with an ohmmeter. Any resistance at all indicates a problem. Repair as necessary.

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P0171 OBD-II Trouble Code Technical Description System Too Lean (Bank 1) What does that mean? Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1. The P0171 is one of the more common trouble codes. This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code. You'll want to also read our article on short and long term fuel trims to help understand the operation of the engine. Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time. This diagnostic trouble code (DTC) is a generic OBD-II powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may vary depending on the model. Symptoms You will more than likely not notice any drivability problems, although there may be symptoms such as: a lack of power detonation (spark knock) rough idle hesitation/surge on acceleration. Causes A code P0171 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum or PCV line/connection Faulty or stuck open PCV valve Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor Possible Solutions A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include: Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling Inspect all vacuum and PCV hoses, replace/repair as required Inspect all hoses and connections in the air intake system Inspect and/or test the intake manifold gaskets for leakage Check for a dirty fuel filter and proper fuel pressure Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool If you have access, you may want to run a smoke test

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P0191 Fuel Rail Pressure Sensor Circuit Range/Performance

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P2197 O2 Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 1) Code OBD-II Trouble Code Technical Description O2 A/F Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 1) What does that mean? This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model. On some vehicles, such as Toyotas, this is actually referring to A/F sensors, Air/Fuel ratio sensors. Which are basically more sensitive versions of oxygen sensors. The powertrain control module (PCM) monitors the air/fuel ratio of the exhaust using oxygen (O2) sensors, and tries to keep things at the normal air/fuel ratio of 14.7:1 via the fuel system. The oxygen A/F sensor outputs a voltage reading that the PCM uses. This DTC is set when the air/fuel ratio as read by the PCM is lean (too much oxygen in the mixture) and has strayed so far from 14.7:1 that the PCM can no longer correct it. This code specifically refers to the sensor between the engine and catalytic converter (not the one behind it). Bank #2 is the side of the engine that does not contain cylinder #1. Note: This DTC is very similar to P2195, P2196, P2198. If you have multiple DTC codes, always fix them in the order they appear. Symptoms For this DTC, the malfunction indicator lamp (MIL) will illuminate. There may be other symtoms. Causes Potential causes of a P2197 code include: Oxygen (O2) or A/F ratio sensor or sensor heater malfunction Open or short in O2 sensor circuit (wiring, harness) Fuel pressure or fuel injector problem Faulty PCM Intake air or engine vacuum leaks Faulty fuel injector(s) Fuel pressure too high or too low PCV system leak/fault A/F sensor relay faulty MAF sensor malfunction ECT sensor malfunction Fuel pressure too low Fuel leak Air suction in air intake system Diagnostic Steps & Possible Solutions Use a scan tool to get readings from the sensor, and monitor the short and long term fuel trim values and O2 sensor or Air Fuel Ratio sensor readings. Also, look at the freeze frame data to see the conditions at the time the code was set. That should help determine if the O2 AF sensor is operating correctly. Compare with manufacturers values. If you don't have access to a scan tool, you could use a multimeter and back-probe the terminals on the O2 sensor wiring connector. Check for shorts to ground, short to power, open circuits, etc. Compare specs with manufacturers specifications. Visually inspect the wiring & connectors leading to the sensor, check for loose connectors, wires rubbed/chaffed, melted wires, etc. Repair as necessary. Visually inspect vacuum lines. You can also test for vacuum leaks using propane or carburetor cleaner along the hoses while the engine is running, if the RPMs change you likely found the leak. Be very careful if doing that, and have a fire extinguisher within reach in case something goes wrong. For example, on a bunch of Ford vehicles, the hose that goes from the PCV to the throttle body can melt causing P2195, P2197, P0171, and/or P0174 codes. If a vacuum leak is determined to be the problem, it would be prudent to replace all vacuum lines if they are getting older, becoming brittle, etc. Use a digital volt ohm meter (DVOM) to check other sensors mentioned such as MAF, IAT, for proper operation. Perform a fuel pressure test, verify readings against manufacturers specification. If you're on a budget and you only have an engine with more than one bank and the problem is only with one bank, you could swap the sensor from one bank to the other, clear the code, and see if the code is followed to the other bank. That would tell you it is the sensor/heater itself that's failed. Check for outstanding technical service bulletins (TSB) for your vehicle, in some cases the PCM can be recalibrated to fix this (not a common fix though). TSBs could also call for replacement of the sensor. When replacing oxygen / AF sensors, be sure to use a high quality ones. In many cases non-OEM sensors are of lesser quality and will not perform correctly. We strongly recommend you stick with OEM brand replacements.

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P0300 Random/Multiple Cylinder Misfire Detected P0301 Cylinder 1 Misfire Detected P0302 Cylinder 2 Misfire Detected P0303 Cylinder 3 Misfire Detected P0304 Cylinder 4 Misfire Detected P0305 Cylinder 5 Misfire Detected P0306 Cylinder 6 Misfire Detected P0307 Cylinder 7 Misfire Detected P0308 Cylinder 8 Misfire Detected P0309 Cylinder 9 Misfire Detected P0310 Cylinder 10 Misfire Detected P0311 Cylinder 11 Misfire Detected P0312 Cylinder 12 Misfire Detected P0313 Misfire Detected with Low Fuel P0314 Single Cylinder Misfire (Cylinder not Specified) P0315 Crankshaft Position System Variation Not Learned P0316 Misfire Detected On Startup (First 1000 Revolutions)

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P2195 O2 Sensor Signal Stuck Lean Bank1 Sensor 1 P2196 O2 Sensor Signal Stuck Rich Bank1 Sensor 1 P2197 O2 Sensor Signal Stuck Lean Bank2 Sensor 1 P2198 O2 Sensor Signal Stuck Rich Bank2 Sensor 1

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it sounds like a faulty oxygen/o2 sensor

02 sensor circuit low voltage ---answer is copied from obd-codes .com you can visit this site for more information if necessary Usually rear o2 sensor problems won't cause drivability issues since they are an input that measures catalyst efficiency (unlike front o2 sensors). However if you have other codes present, like lean codes or pre-o2 sensor codes, then they may cause drivability problems as well as P0143. The following symptoms may be present: MIL (Malfunction Indicator Lamp) illumination Engine performance issues Engine running rough Engine running rich (only if PCM is trying to add fuel to compensate for low o2 sensor voltage reading) Engine running lean (only if vacuum leak is large enough that PCM can't compensate by adding fuel) Poor idle Causes If you have reason to believe that your engine is running lean, fix that problem first, then clear codes and see if the P0157 code resets. An engine that is running lean could set this code, but usually there will be lean codes (P0171, P0174) present. The following could be causes: Air leaks in exhaust in front of o2 sensor giving false reading Engine running excessively lean O2 sensor connector damaged/corroded O2 sensor signal circuit is shorted to ground O2 sensor ground circuit is open O2 sensor has failed (it may be contaminated with fuel or coolant) PCM has failed

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check the under hood fuse box there is a fuse in there marked sensor it sends power to the o2 sensors

Don't know if this will answer it. O2 sensors send info to the computer to make adjustments to the emissions system. Over time the O2 sensors fail which cause the computer to light the "Check engine" light. Originally the "Check engine" light was dedicated to an emission system fault. Now manufactures use it for a variety of abnormalities. To know what the "check engine" light means you have to either take it to a mechanic or buy a OBDII scanner (around $100) and read the code yourself. I like to read my own codes. These scanners are good for all modern cars. Instructions are included EZ to follow.
Long story short, don't worry about it the check engine light will come on when O2 sensor fails. Happy motoring!

There seem to be 4 sensors along the way in the air intake and emissions system.

My Check Engine light indicated a bad sensor 1, bank 2 code (I think).

I had my mechanic replace the sensor that was indicated as faulty... cost = $191.

Then the Check Engine light came on again (with a different code), and I had to leave the van with him all day.

Cost to replace and install that sensor = $115.

My advice: if the Check Engine light stays on *AND* your vehicle is riding rough, get it fixed.

Otherwise, put a piece of tape over that Check Engine light and save a couple hundred dollars!

Hope this helps, I do trust my mechanic fully.

Run fuel system cleaner through it, you have dirty injectors is all!!