SOURCE: check engine light 2003 BMW 325i
both codes are for lean mixture ... bank one and bank two .....that usually means a vacuum leak in the air intake system ... there is a Y shapped boot off the throttle body that fails frequently .. look for a hole or tear or general deterioration ... there is a second boot after the MAF (mass air flow) sensor, that is another possibility ... any off the vacuum hoses you can see under the fancy cover plate could be leaking .. there is a "crank case breather diaphram" that can do the same ... you can test that by removing the oil filler cap slowly (running) ..there should be a sllight vacuum release ... if its a big vacuum whoosh and maybe engine stumbling then suspect the crank case breather diaphram ... finally you could have a bad MAF sensor but more likely the vacuum leak ... running with a lean mixture can eventually damage valves and valve seats ... i use a small rubber hose to my ear to find vacuum leaks (stethoscope) ...
SOURCE: POSSIBLE REASON AND SOLUTIONS FOR CODE PO.500,P1083, PO171,PO174
Table of Contents
Sec. 1. P0171
Sec. 2. P0174
Sec. 3. P0500
Sec. 4. P1083 (a BMW-specific DTC Code)
SEC. 1
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P0171 OBD-II Trouble Code
Technical Description
System Too Lean (Bank 1)
Basically this means that an oxygen sensor in bank 1 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.
Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
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), and/or a 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 Solutions
Possible solutions include:
In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 if necessary
Check for a dirty fuel filter and proper fuel pressure
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Sec. 2
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P0174 OBD-II Trouble Code
Technical Description
System Too Lean (Bank 2)
Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.
Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.
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), and/or a hesitation/surge on acceleration.
Causes
A code P0174 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 can 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 Solutions
Possible solutions include:
In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 if necessary
Check for a dirty fuel filter and proper fuel pressure
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Sec. 3
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P0500 OBD-II Trouble Code
Technical Description
Vehicle Speed Sensor Malfunction
Basically this means that the vehicle's speed as read by the Vehicle Speed Sensor (VSS) is not working properly.
Symptoms
Symptoms of a P0500 DTC may include:
loss of anti-lock brakes
the "anti-lock" or "brake" warning lamps on the dash may be lit
the speedometer or odometer may not work properly (or at all)
your vehicle's RPM limiter may be decreased
the shifting of an automatic transmission may become erratic
other symptoms may also be present
Causes
A code P0500 may mean that one or more of the following has happened:
The Vehicle Speed Sensor (VSS) is not reading (functioning) properly
There is a broken/frayed wire leading to the vehicle speed sensor
The vehicle's PCM is not correctly configured for the actual tire size on the vehicle
Possible Solutions
The simplest thing to do is to reset the code and see if it comes back.
Next, check all wiring and connectors that lead to the speed sensor. The location of the sensor depends on your vehicle. The sensor could be on the rear axle, transmission, or perhaps the wheel hub (brake) assembly.
If the wiring and connectors are OK, then check the voltage at the speed sensor. Again, the exact procedure wil depend on your make and model of vehicle.
If everything looks OK, replace the sensor.
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Sec. 4 - the BMW-specific code
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P1083
Fuel Control Mixture Lean (Bank 1 Sensor 1)
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