Error Code P0070: What It Means & What To Do?

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It you are experiencing troubles with the engine starting or facing hard starts and idles along with check engine light being illuminated on the dashboard, this might be due to OBD code P0070 being stored and flashing onto the Powertrain Control Module (PCM) due to faulty Ambient Air Temperature Sensor.

The Power Control Module (PCM) extracts information from the Ambient Air Temperature sensor to monitor and balance the ambient air temperature with the intake air temperature. If the Power Control Module (PCM) reads that the ambient air temperature and intake air temperature are not at the correct levels, the PCM stores the P0070 code and the Check Engine Light illuminates on the dashboard to inform the owner about a certain problem.
This sensor also helps the Powertrain Control Module (PCM) to determine how much fuel to use on start-up. If this information is wrong then you might face rugged start-ups and hard idles and the sensor is not able to read the outside temperature correctly. The PCM also uses this signal as a logic reference for other temperature sensors on the engine. If the PCM detects an issue with the signal from this sensor, it will set code P0070.

What causes problem with the Ambient Air Temperature Sensor Circuit?

• Failed/Faulty Ambient Air Temperature Sensor
• Broken or shorted out electrical wirings
• Corroded Electric circuitry and system connectors
• Ambient Air Temperature harness open or shorted
• Dirty sensors and circuit components

1. Powertrain Control Module - Faulty PCM will not be able to interpret the data correctly and affect the Engine Control Unit (ECU) and the Throttle Control Unit. Get the faulty electricals replaced now!
2. Air Intake Temperature Sensor - Damaged Air Intake Temperature sensor will be unable to read the temperature of the air entering the system and hamper the engine performance. Thus, replace it now!
3. Ambient Air Temperature Harness - A faulty harness will affect the functioning of the sensor and will result in reduced engine performance. Replace it immediately.
4. Electronic Control Unit - Faulty ECU will hamper the ignition system and thus the overall vehicle’s performance. Replace it now!
5. Instrument Cluster - If the instrument cluster is damaged/faulty, replace it immediately.
6. Diagnostic Tools - Detect and resolve OBD error code issues by using professional grade scanning and diagnostic tools. Buy now!

Mostly, the only indication of a problem with the ambient air temperature sensor will be the Check Engine Light On, on the dashboard. Another symptom can be the Climate Control System (heat and/or air condition controls) that will not work properly.

Common Symptoms

• Check Engine/Service Due Light On
• Air Conditioning not working properly
• Instrument cluster might not detect outside temperature properly
• Overhead console may also not read the outside temperature accurately

• Replace/Repair broken or shorted wires
• Removing corrosion from connector and/or electric circuitry
• Replacement of the Ambient Air Temperature sensor

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• If Ambient Air Temperature exceeds intake air temperature, a code is stored and a service engine soon lamp is illuminated. You will need a scanner or a code reader and a digital volt ohmmeter to successfully diagnose this code.
  
• Begin your diagnosis by visually inspecting all wiring and connectors and look for shorted or burned wiring and replace circuitry and connectors.
• If the system wiring, connectors, and components appear to be in normal working order, connect the scanner to the diagnostic connector and record all stored trouble codes and freeze frame data and clear the codes. After the codes are cleared, test run the vehicle to see if the code returns. If the code fails to immediately return, you may have an intermittent condition.
• Unplug the electrical connector from the ambient air temperature sensor and testing for reference voltage which is usually 5-volts.
• Next, check the sensor ground wire and if both the reference signal and the ground signal are present, test the sensor resistance using the manufacturer’s temperature to resistance specification chart.
• Compare your findings to the manufacturer’s specifications and replace the sensor if it fails to comply. If the sensor and voltage at the sensor are within acceptable specifications, disconnect the PCM electrical connector and test circuit continuity and resistance between the sensor and the PCM.
• Repair or replace system circuitry and components and retest the system. If all system circuitry and sensors work well, then check for a faulty PCM, which is a rare scenario and PCM replacement will require reprogramming.

Common mistakes when diagnosing the P0070 code

Perform a visual inspection and testing the car with a scan tool, and other special equipment listed above, will verify your issue before spending money and time replacing the Ambient Air Temperature Sensor unnecessarily.