DTC P00A3 – Charge Air Cooler Temperature Sensor Circuit High (Bank 2).

✅ DTC P00A3 Meaning

P00A300 indicates that the Charge Air Cooler (CAC) Temperature Sensor for Bank 2 is showing a high voltage signal, which usually means the ECM is reading very low temperature (unrealistic / out of range).

This sensor is usually an NTC (Negative Temperature Coefficient) thermistor:

High voltage = high resistance = colder temperature

Common causes: open circuit, poor connection, sensor fault

✅ Common Causes

Electrical / Wiring

Open circuit in signal wire

Loose or corroded connector pins

Broken wire near sensor harness (very common)

Poor ground reference

High resistance in sensor or wiring

Sensor-related

Faulty CAC temperature sensor (Bank 2)

Water/oil contamination inside connector

Mechanical / Intake system

(Not very common but possible)

Charge air cooler clogged

Intake air temperature extremely low (rare unless subzero climate)

✅ Diagnostic Steps (Step–by–Step)

Follow this sequence in your workshop:

1. Visual Inspection

Locate Bank 2 CAC temperature sensor
(Usually positioned after the intercooler, near throttle body or boost pipe)

Check:

Broken or damaged wire insulation

Loose connector

Corrosion or oil contamination

Aftermarket modifications (intake, intercooler, etc.)

2. Check Live Data on Scanner

Monitor Charge Air Cooler Temperature Bank 2:

If reading is very low (-30°C to -40°C) → circuit open

If reading is normal only sometimes → intermittent wiring fault

Compare:

Bank 1 vs Bank 2

IAT Sensor vs CAC temperature sensor

3. Sensor Voltage Test

With ignition ON:

Signal wire should read around:

4.5–5V (open circuit)

0.5–3.5V (normal operating range)

If you see near 5V, the sensor signal is open.

4. Resistance Test of Sensor (Cold Engine)

Disconnect sensor:

Typical values for NTC thermistor:

20°C → 2k–3k ohms

Lower temps → higher ohms

If:

Infinite resistance (OL) → sensor open → replace

Value way above specification → replace

5. Continuity Test (Wiring)

Check wiring between:

Sensor signal → ECM pin

Sensor ground → ECM ground

Look for:

Open circuit

High resistance (>1 ohm)

Short to 5V reference

✅ Most Common Fixes

Based on workshop experience:

1. Replace charge air cooler temperature sensor (Bank 2)
(Most common root cause)

2. Repair broken wiring near sensor harness
Especially near pipe area where vibration causes wire break.

3. Clean corroded connector and apply dielectric grease

4. Repair open circuit in signal or ground wire

🔧 Quick Technician Tip

If you unplug the sensor and the value on the scanner does not change, the wiring or ECM is faulty.

If the value drops to normal when you jumper the wires with a resistor, the sensor itself is faulty.

Welcome To Madurai Car Service 💐🙏.