P00A5

Intake Air Temperature Sensor 2 Circuit Bank 2

P00A5 is a generic OBD-II powertrain diagnostic trouble code: Intake Air Temperature Sensor 2 Circuit Bank 2. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P00A5
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P00A5 means

DTC P00A5 is a generic OBD-II powertrain code indicating a general circuit malfunction in the Intake Air Temperature (IAT) Sensor 2 circuit on Bank 2 — the side of the engine not containing cylinder #1. Unlike the more specific sub-codes (P00A6 range/performance, P00A7 circuit low), P00A5 is the umbrella fault indicating the PCM has detected a signal that falls outside its acceptable operating window without the cause being further classified. The IAT sensor 2 is typically positioned after the mass air flow (MAF) sensor or in the intake manifold and measures the temperature of air entering the combustion chambers. Using this reading alongside MAF and MAP sensor data, the PCM calculates accurate air density for injection timing and fuel quantity decisions. When IAT2 Bank 2 data is deemed invalid, the PCM substitutes a default value, which can degrade combustion efficiency and increase emissions. In some applications the sensor is integrated into the MAF sensor assembly, making it critical to verify the exact sensor location for the specific vehicle before condemning a standalone component. Prompt diagnosis prevents prolonged operation with substitute fuel-air calibration maps.

Common causes

Most-frequently reported root causes when P00A5 is logged.

  • 1
    Defective IAT sensor 2 with internally failed thermistor element
  • 2
    Sensor displaced or improperly seated in its mounting port, altering the airflow reading
  • 3
    Open or shorted signal wire between IAT2 and PCM on Bank 2
  • 4
    Open ground circuit at the sensor connector
  • 5
    Corroded, loose, or damaged connector terminals
  • 6
    IAT2 integrated within a combined MAF/IAT assembly that has failed
  • 7
    PCM fault causing loss of the 5 V reference voltage to the sensor

Symptoms drivers notice

Malfunction Indicator Lamp (MIL) illuminated
Marginally increased fuel consumption as PCM uses default air-temperature substitute values
Slightly reduced engine performance under heavy load
Possible rough idle or hesitation in cold-start conditions
Higher tailpipe emissions (NOx or HC) particularly when cold
No drivability symptoms at all in mild cases where default values closely match actual conditions

How to diagnose P00A5

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool with the engine cold and read the IAT2 Bank 2 live value; it should closely match ambient air temperature and the coolant temperature sensor reading on a cold soak
  2. 2
    Inspect the IAT2 sensor location on Bank 2 — confirm it is properly seated in its bung or port and has not backed out
  3. 3
    Visually inspect the sensor wiring and connector for damage, corrosion, and loose terminals
  4. 4
    Disconnect the IAT2 sensor and measure its resistance with a multimeter; compare to the manufacturer resistance-versus-temperature chart at the known ambient temperature
  5. 5
    With the sensor disconnected and ignition on, verify approximately 5 V appears on the signal wire and that the ground pin shows continuity back to the PCM
  6. 6
    Reconnect the sensor and road-test while logging IAT2 data; abnormal readings that do not track rising engine temperatures confirm a sensor or harness fault

Related powertrain codes

Frequently asked questions

What is IAT Sensor 2 as opposed to IAT Sensor 1?

IAT Sensor 1 is the primary sensor, often integrated in the MAF sensor or air filter housing. IAT Sensor 2 is a downstream sensor positioned closer to the intake manifold or throttle body, providing a more precise in-manifold air temperature reading for combustion management.

Will P00A5 cause my vehicle to fail an emissions test?

Yes — an active MIL automatically fails most emissions inspection regimes. Additionally, the degraded fuel-air control from the loss of valid IAT2 data can raise NOx or hydrocarbon tailpipe emissions above legal limits.

Is P00A5 the same on all vehicle makes?

The SAE code definition is generic, but the sensor location, circuit wiring, and access procedure vary by manufacturer and model. Always consult the vehicle-specific wiring diagram and sensor specifications before replacing parts.

Can a vacuum or boost leak trigger P00A5?

Not directly — P00A5 is an electrical circuit fault. However, a boost or vacuum leak that exposes the sensor to extreme temperature transients could contribute to an associated range/performance code such as P00A6. P00A5 itself points to an electrical signal problem.

Disabling P00A5 in software

RaceTune can permanently disable P00A5 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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