P0105 - MAP Circuit Malfunction
OBD-II Trouble Code Technical Description
Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.
The MAP (Manifold Absolute Pressure) sensor is part of the fuel management system. It reacts to changes in engine manifold pressure. The PCM (Powertrain Control Module) monitors the MAP sensor continually to properly run the engine. Changes in engine load require changes in the amount of fuel injected, and timing of the ignition system, etc.
An engine under load has more manifold pressure(or less vacuum) than an engine that is coasting. As the load changes, the MAP sensor voltage signal to the PCM changes accordingly. To check the MAP sensor operation, though, the PCM watches other sensors to verify that the MAP sensor is working properly.
For example, the PCM compares the TPS (Throttle Position Sensor) signal to the MAP signal to verify the MAP signal isn't "sticking". If the PCM doesn't see a MAP sensor change immediately follow a change in the throttle pedal sensor, it knows there is a problem with the MAP sensor and sets P0105. Or, if the PCM notices that the TPS indicates the engine is under load, but the MAP signal indicates that the engine is "coasting" it, again, knows there is a problem with the MAP sensor or TPS and sets P0105.
Symptoms
Symptoms of a P0105 check engine light code may include:
Poor running engine Engine runs rich Engine won't idle Engine backfires through tailpipe Engine misfire under load or at idle MIL (Malfunction Indicator Lamp) illumination In some extreme cases there may be no symptoms other than MIL illumination
A typical MAP sensor
Causes
A P0105 DTC could be caused by:
MAP sensor vacuum hose disconnected or plugged Bad MAP sensor Bad TPS Damaged or problematic MAP sensor connector Damaged or problematic TPS connector Damaged wiring Short to reference voltage on signal circuit of MAP sensor Loss of ground to MAP sensor or TPS Open on signal circuit of MAP sensor Bad PCMPossible Solutions
Using a scanner or code reader, turn the ignition on and engine OFF; what does the MAP sensor voltage read? It should be about 4 Volts for sea level. If you are at a higher altitude, it should decrease about half a volt or so for each 1,000 ft. of altitude (this will vary from model to model) Or if you have a separate MAF (Mass air flow) sensor on your vehicle, they are usually equipped with a Barometric pressure reading. If so, the Baro reading should match the MAP reading (they both measure ambient air pressure). If they're roughly equal, then, check for Freeze Frame data of the MAP sensor (if available).
NOTE: Freeze Frame data is the PCM recording a fault when it happens. It captures the readings of the various PIDS (parameter identifiers)available to troubleshoot what happened. It's like a recording of the problem as it happened. At idle a typical MAP sensor Voltage reading should be about a volt, and at WOT (wide open throttle) it should approach 4.5 to 5 Volts. As for the TPS, at idle, the voltage reading is about 1 Volt or less. As the throttle is opened the reading will increase to 4.5 Volts at WOT. Do the two readings make sense? For example, if the TPS reading on Freeze Frame data shows 2.5 Volts (indicating partial throttle) does the MAP sensor indicate a reading that isn't at either extreme? Using the Freeze Frame data (if available) compare the MAP reading to the TPS when the problem occurred. This can help you identify what happened
If you have no access to Freeze Frame data then check if the MAP sensor voltage changes when you apply vacuum to it. You can do this by mo
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