Some owners of various Mazda vehicles (2011 Mazda2, 2004-2011 Mazda3, 2012 Mazda5, 2003-2011 Mazda6, 2007-2011 Mazda CX-7 and CX-9, 2009-2011 Mazda MX-5 and 2004-2011 Mazda RX-8) may complain that the ambient temperature display is not accurate, or that it takes too long for the display to show actual temperature.
First verify the condition. If the condition is similar to the following “CONTROL LOGIC OF AMBIENT TEMPERATURE” or “DIFFERENCE BETWEEN THE TEMPERATURE DISPLAY AND OTHERS,” advise the customer that this is a normal characteristic and is not a malfunction. If the condition does not meet the following and the sensor malfunction is suspected, be sure to inspect the sensor according to MS3 online or workshop manual (section 09-22 AMBIENT TEMPERATURE SENSOR INSPECTION). Replace the sensor only when it fails the workshop manual inspection.
CONTROL LOGIC OF AMBIENT TEMPERATURE
The ambient temperature display is NOT always equal to the reading of the temperature sensor mounted in the front of the vehicle.
Under certain conditions, the sensor reading is adjusted in order to avoid false high reading due to heat from the engine and/or road surface.
The ambient temperature display is adjusted during the conditions shown below.
Due to this adjustment, the temperature on the display may temporarily differ from actual.
EXAMPLE OF CONDITIONS WHEN SENSOR READING IS ADJUSTED
CONDITION 1: Engine coolant temperature when ignition switch is on
Low engine temp. …Actual sensor reading
High engine temp. …The last temperature recorded when ignition was off
NOTE: The threshold of the engine temp. differs depending on car model, but is approximately 122 – 140 deg. F
Condition…Reason for adjustment
High engine temp. …Especially in summer, the display may show false high temperature due to heat from the road surface.
CONDITION 2: Vehicle speed
Low vehicle speed…The last temperature recorded
High vehicle speed…Actual sensor reading
NOTE: The threshold of the vehicle speed differs depending on car model, but it is approximately 3 mph – 15 mph
CONDITION 3: Ambient temperature change
Low ambient temp…Gradually changes to actual sensor reading
High ambient temp. …Immediately changes to actual sensor reading
Condition…Reason for adjustment
Low ambient temp. …When moved from garage/indoor parking to outside, it may take a longer time to show actual ambient temperature
NOTE: When M-MDS is connected, the ambient temperature shown on M-MDS is the actual temperature sensor value. However, in some cases it may not match the instrument cluster display because the value may be adjusted. DO NOT attempt repair due to this difference.
If the temperature sensor connector is disconnected then connected, the recorded temperature is lost and the display starts to show actual sensor reading regardless of the condition. Sometimes it is misjudged that the symptom is fixed by the sensor replacement, but actually the display has reset and now shows the actual sensor reading because the connector was disconnected.
DIFFERENCE BETWEEN THE TEMPERATURE DISPLAY AND OTHERS
If the vehicle’s temperature display does not match an external temperature display (such ads a bank sign showing outside temperature), this is because the external temperature display does not always show the temperature around the vehicle.