P00A8
Intake Air Temperature Sensor 2 Circuit High Bank 2P00A8 is a generic OBD-II powertrain diagnostic trouble code: Intake Air Temperature Sensor 2 Circuit High 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.
What P00A8 means
DTC P00A8 is stored when the Powertrain Control Module (PCM) detects a signal voltage from the Bank 2 Intake Air Temperature Sensor 2 (IAT2) that is higher than the expected calibrated threshold — typically above 4.9–5 V, which corresponds to an impossibly cold reading. The IAT2 sensor is a negative-temperature-coefficient (NTC) thermistor: its resistance decreases as temperature rises, pulling the reference voltage signal down. A persistently high signal therefore indicates an open circuit, broken sensor element, or a disconnected/corroded connector rather than genuinely frigid air. Bank 2 is the cylinder bank that does not contain cylinder #1 on V-configuration engines. The PCM relies on IAT input, together with the Mass Airflow (MAF) sensor, to calculate the correct fuel injection pulse-width and ignition timing. When IAT2 reports an implausibly cold temperature, the PCM may over-enrich the mixture, resulting in elevated hydrocarbon emissions, reduced fuel economy, and rough running. The fault is non-critical but should be addressed promptly; left unattended, persistent over-fuelling can foul spark plugs, load the catalytic converter, and cause secondary codes to set.
Common causes
Most-frequently reported root causes when P00A8 is logged.
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1
Failed or open-circuit IAT2 sensor on Bank 2 (most common — broken thermistor element)
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2
Open wire or broken conductor in the IAT2 signal circuit between sensor and PCM
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3
Corroded, loose, or pushed-out terminal in the IAT2 sensor connector
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4
Open ground circuit for the IAT2 sensor preventing voltage reference from being pulled down
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5
Chafed wiring harness causing an intermittent open on the signal wire
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6
Water or oil intrusion into the sensor connector degrading electrical contact
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7
PCM internal fault on the IAT2 input channel (rare; diagnose last)
Symptoms drivers notice
How to diagnose P00A8
A typical diagnostic flow when this code is present.
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1
Connect an OBD-II scan tool, confirm P00A8 is active or pending, and record freeze-frame data including IAT2 voltage and coolant temperature at the time of the fault
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2
With the key on and engine cold, compare the IAT2 reading to the coolant temperature sensor (CTS) reading — they should be within a few degrees of each other; a reading near -40 °C / -40 °F strongly suggests an open circuit
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3
Visually inspect the Bank 2 IAT2 sensor, wiring harness, and connector for corrosion, cracking, oil contamination, pushed-out terminals, or mechanical damage
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4
Using a multimeter, unplug the sensor and measure its resistance across the two terminals at known ambient temperature; compare against the OEM resistance-vs-temperature table (typically 2–3 kΩ at 20 °C) — infinite resistance confirms an open sensor
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5
With the sensor plugged in and ignition on, backprobe the signal wire and verify a reference voltage of approximately 5 V from the PCM; then verify the ground circuit measures less than 0.1 Ω to chassis ground
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6
Perform a wiggle test on the harness and connector while monitoring live IAT2 voltage; sudden voltage spikes indicate an intermittent open in the wiring
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7
Replace a confirmed faulty IAT2 sensor or repair the open circuit, clear codes, and complete a drive cycle to verify the repair
Related powertrain codes
Frequently asked questions
What does 'Circuit High' mean for P00A8?
"Circuit High" means the PCM is seeing a signal voltage near the top of its measurement range (close to the 5 V reference supply). For an NTC thermistor like the IAT sensor, high voltage means very high resistance, which the sensor would only produce at extremely cold temperatures. In practice this usually points to an open circuit — a broken wire or failed sensor — rather than genuinely arctic air.
Is P00A8 safe to drive with?
The vehicle is generally driveable because the PCM can substitute a default IAT value, but fuel trims and timing may be incorrect, causing poor economy and elevated emissions. It is not an emergency, but the fault should be fixed within a few days to avoid secondary issues such as fouled catalytic converters.
What is Bank 2 on a V-engine?
On a V6, V8, or V10 engine, Bank 1 contains cylinder #1 and Bank 2 is the opposite cylinder bank. On inline (four-cylinder) engines there is no Bank 2, so this code will only appear on V-configuration or horizontally-opposed engines.
Can a bad MAF sensor trigger P00A8?
Indirectly, a failed MAF can cause a cluster of air-metering codes, but P00A8 is specifically tied to the IAT2 circuit voltage. If both MAF and IAT codes are present together, inspect the shared wiring harness and connector ground first before replacing sensors individually.
Disabling P00A8 in software
RaceTune can permanently disable P00A8 — 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.
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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