P0540

Symptoms

• Difficulty cold starting the engine
• White or black smoke from the exhaust pipe when starting
• Unstable operation at idle after a cold start
• Check Engine Light Illuminates
• Extended engine warm-up time

Causes

• Malfunction of the heating element of the air heater
• Open or short circuit in the heater circuit
• Heater relay malfunction
• Connector oxidation or wiring damage
• ECU malfunction (rare)

How to Fix

1. Check the intake air heater circuit fuse and relay.
2. Measure the resistance of the heating element (must meet specification)
3. Check the presence of power and ground at the heater connector
4. Inspect the wiring for damage or contact oxidation
5. Replace the heating element or relay if a fault is detected
6. Reset the error code and test for cold starting

Related codes

Error P0540 by Vehicle Brand