Code P00A3: Definition and Symptoms
The generic diagnostic trouble code P00A3 indicates that the Powertrain Control Module (PCM) has detected an abnormally low voltage value in circuit 2 of the Charge Air Cooler Temperature (CACT) sensor. This code, applicable to many brands (Ford, VW, Audi, Toyota, etc.), generally signals an open circuit problem or a short circuit to ground on the engine bank that does not include cylinder number 1.
Common Symptoms
- Check Engine Light illuminated
- Poor performance and power loss
- Reduced fuel economy
- Limp mode activated
- Diesel particulate filter regeneration inhibited
Possible Causes of P00A3 Fault
- Faulty CACT sensor (most common cause)
- Wiring problem: open circuit, short circuit, corroded or loose connector
- Faulty or clogged charge air cooler
- Internal PCM failure (rare)
Diagnosis and Repair Procedures
Always start with a visual inspection of the connectors, wiring, and air ducts for obvious damage.
Preliminary Test with Diagnostic Tool
Using a scan tool, monitor the CACT sensor data. Unplug the connector: the displayed value should drop. Then, bridge the connector terminals with a jumper wire: the value should then spike. If this happens, the circuit is healthy and the sensor is most likely faulty.
CACT Sensor Test
Disconnect the sensor and measure its internal resistance (Ohms) with a multimeter. Compare the value to those specified by the manufacturer for a given temperature. An infinite resistance (open circuit) or zero resistance (short circuit) confirms a faulty sensor.
Electrical Circuit Test
Check for the presence of the 5V reference voltage and the PCM ground at the sensor connector (ignition on). An absence of reference voltage or a faulty ground (OL in continuity test) indicates a wiring problem or, more rarely, a PCM failure.
Related Codes
- P00A0: CACT Circuit Bank 2
- P00A1: CACT Circuit Range/Performance Bank 2
- P00A2: CACT Circuit Low Value Bank 2
- P00A4: CACT Circuit Intermittent Bank 2
Need help diagnosing your vehicle? Consult a professional equipped with a diagnostic tool suitable for your brand for accurate and efficient troubleshooting.