Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car has a part that helps keep the engine clean by removing gases. This part has a heater that isn't working because the connection is broken.
The P142C code indicates that the engine control module (ECM) has detected an open circuit in the crankcase ventilation heater relay. This means that the relay is not completing the electrical circuit, which is necessary for the heater to function properly.
The crankcase ventilation system helps manage and recycle gases that escape from the engine. It includes a heater to prevent these gases from freezing in cold conditions. The ECM monitors the relay that controls this heater. If the relay circuit is open, the ECM triggers the P142C code.
• Check Engine Light illuminated
• Possible poor engine performance
• Potential increase in emissions
• Faulty crankcase ventilation heater relay
• Damaged wiring or connectors in the relay circuit
• Blown fuse for the crankcase ventilation heater
ECM: Engine Control Module
Relay: An electrical switch that opens and closes under the control of another electrical circuit
• Scan the vehicle for codes and freeze frame data.
• Inspect the wiring and connectors for the relay.
• Test the crankcase ventilation heater relay for continuity.
• Replace the faulty crankcase ventilation heater relay.
• Repair or replace damaged wiring or connectors.
• Replace any blown fuses related to the system.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $250
Moderate
• BMW 3 Series
• BMW 5 Series
• BMW X5
• Regularly inspect and maintain the crankcase ventilation system.
• Check electrical connections for corrosion or damage.
• Replace relays and fuses at recommended intervals.
Electrical Circuit Issue
• Have the vehicle inspected by a professional mechanic.
• Avoid driving in extremely cold conditions until repaired.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code is more commonly reported in colder climates where the crankcase ventilation heater is more frequently used.
Moderate – The vehicle can still be driven, but it should be repaired to prevent potential engine issues.
Ignoring this issue could lead to increased emissions, which may violate local environmental regulations.
• Vehicle should be at operating temperature.
• Test in a controlled environment to avoid false readings.
The crankcase ventilation heater relay is typically located in the engine bay, near the fuse box or the engine control module.
Q: Can I drive with a P142C code?
A: Yes, but it's advisable to fix the issue soon to avoid potential engine damage.
Q: What happens if I ignore this code?
A: Ignoring the code may lead to increased emissions and potential engine performance issues.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.