I have a 2001 Boxster and recently replaced both O2 sensors when a check engine fault code identified one faulty O2 sensor. The car runs fine but the check engine light keeps coming on after about 200 kilometres of driving. The same fault codes keep coming up P1128 and P1130 but the garage can't find the problem. We keep erasing the code and the check engine light stays off for about 200 kilometres and then comes on while driving for no identifiable reason.
It sounds like you may have a failing Mass Air Flow sensor, seems like Ive been seeing these tied together quite often. Its a little tricky but a good repair shop should be able to test this sensor. I dont want to tell you to replace it without having it tested cause they are a bit pricey but check around, you never know. Hope this give youu another idea where to look.
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These codes, po 138 bank 1 sensor 2 shorted to voltage and code po158 means bank 2 sensor two shorted to voltage. these are the two rear oxygen sensors in the exhaust system. there two up frt and two in the rear, check the wiring on the two rear sensors, make sure that the wiring is not cut or stuck between metal. if the wiring is good then replace both rear sensors, when you get them ask for the left and right after the cat sensors. or bk1 s2 and bk2s2. after replacing them reset the computer. go to an auto parts sotre or if you have a code reader you can do it. hope this helps good day.
Hello! Both faults are pointing at the same Oxygen Sensor...Upstream Bank 2...Meaning in the exhaust header before the Cat. converter on the right side of the engine...O2 sensors generally cause a P-code as an effect rather than a cause...But in this instance it's a defective O2 Sensor...Replace...
CODE P0421. DEFINITION-CATALYST EFFICIENCY LOW-BANK 1.
EXPLANATION-THE OXYGEN SENSORS MONITOR THE CATALYTIC CONVERTERS ABILITY
TO STORE OXYGEN. PROBLEM CAUSES- 1. CATALYTIC CONVERTER DEFECTIVE
(FAILURE POSSIBLY DUE TO #2,3, OR 4) 2. ENGINE MISFIRE OR RUNNING
CONDITION. 3. LARGE VACCUM LEAK 4. ENGINE OIL LEAKAGE INTO
EXHAUST-VALVE GUIDE SEALS, PISTON RINGS. THE PCM HAS DETERMINED THAT
THE WARM UP CATALYST EFFICIENCY FOR BANK 1 IS BELOW TRESHOLD FOR THE
CURRENT ENGINE OPERATING CONDITION. (BANK 1 IDENTIFIES THE LOCATION OF
CYLINDER #1, WHILE BANK 2 IDENTIFIES THE CYLINDERS ON THE OPPOSITE
Take the vehicle to any auto parts store that offers to read the fault codes with a scanner for free and find out what that code is. If it shows Upstream or Downstream O2 sensor replace the O2 Sensor. There is a catch, dodge had an issue in the 2000 - 2004. The ECM will show a fault code that indicates the Catalytic converter is faulty. This is actually a faulty Downstream O2 Sensor. If you get a Catalytic converter fault code replace the O2 sensor first if you still have the problem then replace the converter.
Hello! Which O2 sensor did you change? P0138 and P0140 are indicating Bank #1 Sensor #2... Is this the sensor that was changed? If it was, The sensor is reacting to a different fault...A rich condition will contaminate the sensor; It then generates a fault...Actually the O2 fault is an effect not a cause...
Does the engine run OK? Hard starting, stalls or breaks-up when you give it gas. Give me a little back ground...
There is a common fault on 2001 Nissan's that you can check; Lack of a non-resistive ground to the body...
Use an ohm meter set on the X1 scale...#1 read from negative terminal of battery to body...Then from the engine to the body...Both readings should = Zero ohms...If not .......That's the fault
There are about 100 causes for the service engine light to come on.
Buy an engine code reader and you'll be able to always identify the source of the fault.
This one is less than $50. Plugs in under dash -driver side. Pays for itself in one incident.
If the engine is running without any problems then The fault code which has flagged the checked engine light will either pertain to the upstream O2 sensor, a drop in catalytic efficiency, an EGR issue, or maybe even an EVAP issue.
A lot of EVAP issues can be resolved by simply ensuring that the fuel filler cap is on securely, otherwise a vacuum leak will be detected in the system and the check engine light will come on.
A drop in catalytic efficiency (P0420) is usually temporary and will stay away after a reset.
EGR issues can sometimes be rectified by removing the EGR valve and cleaning it, and the ports on the intake where it was sat, but there are occasions when it has to be renewed.
The O2 sensor issues are a wee bit different. There are a number of fault codes which relate to the O2 sensor, and which make the O2 sensor look faulty, when the O2 sensor is actually attempting to rectify a problem from elsewhere and isn't faulty at all. However, they could also be due to a fault with the O2 sensor. Basically, further checks should be made before condemning the O2 sensor should the fault code relate to the sensor.
Have a code read done and then have the codes reset and see what comes up.