P00A3
Charge Air Cooler Temperature Sensor Circuit High Bank 2P00A3 is a generic OBD-II powertrain diagnostic trouble code: Charge Air Cooler Temperature Sensor 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 P00A3 means
DTC P00A3 is set when the Powertrain Control Module (PCM) detects an abnormally high voltage signal from the Charge Air Cooler Temperature (CACT) sensor located on Bank 2 — the cylinder bank that does not contain cylinder #1. The charge air cooler, commonly called an intercooler, reduces the temperature of compressed air after it exits the turbocharger before it enters the engine intake. The CACT sensor is a thermistor that returns a variable voltage to the PCM so that air density and fuelling can be adjusted accordingly. A high-circuit fault typically indicates an open in the signal or ground wiring, causing the PCM to see an unloaded reference voltage rather than the expected temperature-dependent signal. When this code is active, the PCM can no longer accurately determine post-intercooler air density, which compromises fuelling accuracy, turbocharger management, and — on diesel applications — diesel particulate filter regeneration scheduling. The vehicle may enter a reduced-power (limp) mode to protect the engine from operating with incorrect fuel-air ratios. Prompt diagnosis is recommended to restore full engine performance and prevent secondary issues such as incomplete DPF regeneration cycles.
Common causes
Most-frequently reported root causes when P00A3 is logged.
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1
Faulty or failed charge air cooler temperature sensor (open thermistor element)
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2
Open circuit or broken wire in the sensor signal or ground circuit
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3
Corroded, loose, or damaged sensor connector on Bank 2
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4
Damaged wiring harness chafing against turbocharger or exhaust components
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5
Blocked or physically damaged charge air cooler restricting airflow and causing extreme readings
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6
High-resistance ground path between sensor and PCM
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7
PCM internal fault causing incorrect reference voltage output
Symptoms drivers notice
How to diagnose P00A3
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and record freeze-frame data; note the CACT Bank 2 live reading — an implausibly high value (e.g. above 150 °C at ambient) confirms the high-circuit condition
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2
Perform a visual inspection of the CACT sensor body, harness, and connector on Bank 2 for melting, chafing, corrosion, or backed-out terminals
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3
Disconnect the sensor connector and verify that the scan tool reading drops to the rail-minimum (open-circuit floor), confirming the fault follows the sensor side
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4
With ignition on and connector unplugged, probe the reference wire at the harness side — it should read approximately 5 V; a missing reference indicates a PCM or harness fault
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5
Test ground continuity from the sensor ground pin back to PCM ground with a multimeter; resistance should be under 1 Ω
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6
Measure sensor resistance across its terminals and compare to the temperature-resistance chart in the service manual; infinite resistance confirms an open thermistor
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7
If all circuits test good, check for relevant Technical Service Bulletins and consider PCM software update or replacement as a last step
Related powertrain codes
Frequently asked questions
Can I drive with P00A3 active?
Short distances may be possible, but the vehicle may enter limp mode and fuel efficiency will be reduced. On turbocharged diesel engines, DPF regeneration can also be disrupted, risking DPF blockage over time. Diagnosis and repair should not be delayed.
What is the difference between P00A3 and P00A2?
P00A2 is the low-circuit variant (signal voltage too low, indicating a short to ground or a failing sensor reading maximum temperature), while P00A3 is the high-circuit variant (signal voltage too high, indicating an open circuit or disconnected sensor). Both affect Bank 2 CACT.
How do I know if the sensor itself is bad or if it is a wiring problem?
Unplug the sensor connector and measure resistance directly across the sensor's two terminals. An infinite (open) reading at a known temperature confirms a failed sensor. If resistance is within spec, probe the harness for continuity and reference voltage to isolate a wiring or PCM fault.
Will replacing the intercooler fix P00A3?
Only if the intercooler damage has physically destroyed the sensor or its mounting. P00A3 is an electrical circuit fault — in the vast majority of cases the sensor, wiring, or connector is the culprit rather than the cooler core itself.
Disabling P00A3 in software
RaceTune can permanently disable P00A3 — 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.
ECU families we can disable P00A3 on
We hold the DaVinci A2L disable definitions for these families, so the exact P00A3 path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.
- Bosch EDC17C74 verified
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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