P0073 — Outside Air Temperature Sensor – High Input

The diagnostic trouble code (DTC) P0073 indicates an issue related to the outside air temperature (OAT) sensor sending a higher-than-expected voltage or reading to the Vehicle’s engine control unit (ECU). In simple terms, this means the ECU detects that the outside air temperature sensor is reporting an abnormally high or out-of-range signal. This often points to a problem with the sensor itself, its wiring, or the associated circuitry.

Note: The labeling of this code can vary depending on the vehicle manufacturer. Always verify with the specific OEM diagnostics procedure for precise identification and troubleshooting.

Fast Facts:

System affected: Outside Air Temperature Sensor Circuit

Severity: Moderate – may affect engine management and climate control

Main symptoms: Malfunction indicator light, incorrect temperature readings

Driveability: Limited – may lead to inaccurate engine or climate control responses

Manufacturer variations for trouble code P0073

The P0073 code may be identified differently by various vehicle manufacturers, but generally refers to the same issue related to the outside air temperature sensor high input. Each OEM may have their own label or code variation. Below are some known examples:

Ford: P0073 — Intake Air Temperature Sensor High Input
Volkswagen: 0073 — Intake Air Temp Sensor (G56) — Signal Too High
BMW: 29F3 — Ambient Air Temperature Sensor Circuit High
Honda: P0073 — Intake Air Temperature Sensor Circuit High Input

Always consult the specific repair manual or diagnostic interface for the vehicle to confirm the exact label variation.

What does trouble code P0073 mean?

In simple terms, P0073 means the ECU (the vehicle’s brain) is receiving a reading from the outside air temperature sensor that indicates the air around the vehicle is unusually hot—or the sensor’s signal is higher than it should be. The ECU constantly monitors the input from various sensors to manage engine performance, emissions, and climate control systems. When the input from the outside air temperature sensor hits a value that exceeds acceptable limits or is out of the normal range, the ECU triggers this diagnostic trouble code.

This code is typically set off when the sensor’s voltage signal indicates an abnormally high temperature reading or if the sensor’s circuit sends an unexpectedly high voltage for an extended period. The most common context of appearance involves scenarios where the vehicle experiences unusual temperature readings or during diagnostic testing when sensor data is scrutinised.

Severity and risks of trouble code P0073

The P0073 concern is generally considered **moderate** since it does not directly affect the engine’s ability to operate under normal conditions, but it can influence vehicle systems that rely on accurate outside temperature data. For example, incorrect outside air temperature readings may lead to faulty climate control operation or modify engine parameters unnecessarily, affecting fuel economy and emissions.

**Potential risks** include inaccurate temperature display on dashboards, improper operation of transmission cooling (if integrated), or mismanagement of engine parameters that depend on external temperature data. However, the vehicle can typically be driven with this fault stored in the system, although it’s advisable to address it promptly to prevent potential problems or sensor damage.

**Conclusion:** Limited — the vehicle can usually be driven, but repairs should be scheduled to prevent further issues.

Symptoms of trouble code P0073

The presence of the P0073 code can manifest through various symptoms, often depending on whether the sensor’s fault impacts other vehicle systems. Common indicators include:

Inaccurate outside temperature display: The dashboard’s temperature reading may show implausible values, such as extremely high or low readings that do not match environmental conditions.
Malfunction indicator light (MIL): The check engine light may illuminate to alert the driver of a problem.
Erratic climate control operation: The air conditioning or heater may not respond properly if the systems use outside temperature data for their adjustments.
Potential issues with engine management: In some cases, the engine control settings might be affected, leading to slightly altered idle or throttle responses, especially if the sensor data is used in certain strategies.
Unusual dashboard messages or display errors.

Most likely causes of trouble code P0073

When diagnosing P0073, understanding the root causes helps streamline the repair process. Here are the most common causes, ranked from most to least frequent:

Faulty outside air temperature sensor (G17 or G56): The sensor itself might be defective due to age, damage, or manufacturing defects, providing inaccurate signals.
Damaged or corroded wiring or connectors: Corrosion, broken wires, or poor connections can cause unreliable signals or high voltage readings.
Electrical interference or short circuits: External electrical disturbances or shorts within the circuit can lead to abnormally high signals.
Incorrect sensor installation or wiring errors: A misinstalled sensor or wiring mistakes during previous repairs may cause this fault.
ECU or instrument cluster malfunction: Although rare, a malfunctioning ECU or display unit can misinterpret or falsely register sensor signals.

How to diagnose trouble code P0073

Diagnosing P0073 involves a systematic approach to verify the sensor’s condition and its circuitry. Follow these general steps:

Visual inspection: Check the outside air temperature sensor, wiring, and connectors for damage, corrosion, or disconnection.
Inspect wiring harnesses: Look for signs of wear, fraying, or broken wires that could affect the circuit integrity.
Test sensor voltage and resistance: Using a multimeter, measure the sensor’s resistance and voltage signal according to the manufacturer’s specifications and compare results.
Retrieve live data: Connect an OBD-II scan tool and observe real-time sensor readings, verifying if the temperature readings are consistent with ambient conditions.
Check for other related codes: Scan for additional DTCs that could point to wiring issues or sensor circuit problems.
Conduct wiring continuity tests: Verify the integrity of the wiring harness from the sensor to the ECU connector.
Perform sensor replacement if necessary: Swap the sensor with a known good unit to see if the code clears and readings normalize.

Possible repairs for trouble code P0073

Once the root cause is identified, various repairs can be undertaken. The specific repair depends on the exact fault but generally includes:

Replacing the outside air temperature sensor: A basic repair, suitable for most vehicles; requires some mechanical skill and possibly removal of panels.
Repair or replacement of wiring and connectors: Restoring proper electrical connections is a professional-level repair that involves inspecting, cleaning, or replacing damaged wiring.
Correcting wiring harness damage or interference issues: Professional diagnosis and wiring repair may be necessary if interference or shorts are found.
Updating or resetting the ECU: In rare cases, reprogramming or resetting the vehicle’s ECU may be required—this should be performed by a qualified technician.
Addressing unrelated ECU faults: If the ECU or instrument cluster malfunction causes false readings, further diagnostics and possible component replacement may be needed.

Vehicles commonly associated with trouble code P0073 in Europe

The P0073 code affects a broad range of vehicles, especially those equipped with outside air temperature sensing systems. In European markets, common brands include:

Volkswagen Group: Audi, Volkswagen, Skoda, Seat – various engine types including TDI and TSI.

Ford: Focus, Fiesta, Mondeo, Kuga – especially models with integrated climate and sensor systems.

BMW: Various models with integrated outside temperature sensing units.

Honda, Peugeot, Citroën, Renault: Several models with outside temperature sensors integrated into the ambient climate control systems.

Frequent mistakes with trouble code P0073

Common errors during diagnosis or repair can prolong the problem or lead to misdiagnosis. Being aware of these pitfalls helps improve repair accuracy:

Replacing the sensor without proper diagnostics: This may not solve the issue if wiring or circuit faults are the actual cause.
Overlooking wiring or connector issues: Ignoring wiring damage can lead to recurring faults even after sensor replacement.
Assuming ECU failure without evidence: An ECU fault is rare; most issues involve sensors or wiring.
Failing to test live data properly: Relying purely on code reader data without confirming sensor readings through live data can mislead diagnosis.
Ignoring environmental factors: External electrical interference or recent repairs may temporarily cause high readings that resolve after inspection.

Quick FAQ — trouble code P0073

Can this code disappear on its own? In most cases, no. Once the sensor or circuit issue persists, the code will remain unless repaired. However, clearing the code with an OBD-II scanner may reset the error temporarily, but it is likely to return if the underlying problem is not fixed.

Can I keep driving? Yes, generally the vehicle can be driven with this code stored. It does not usually affect the core engine operation, but the driver may notice inconsistent outside temperature readings or climate control issues.

Why does the code return after clearing it? The fault is persistent and caused by a failed sensor, damaged wiring, or circuit problems. If these issues are unresolved, the code will reappear shortly after clearing.