P221C – BMW DTC

BMW DTC P221C – Reductant Heater ‘B’ Current Too Low

DTC P221C meaning on BMW

DTC P221C on a BMW indicates that the reductant heater ‘B’ current is too low. The reductant heater is responsible for heating the diesel exhaust fluid (DEF) to optimize its performance in reducing emissions. When the current flowing through the reductant heater ‘B’ is below the expected threshold, the P221C trouble code is triggered.

BMW DTC P221C symptoms

Symptoms of DTC P221C on a BMW may include:

• Check Engine Light (MIL) illuminated
• Reduced engine performance
• Increased emissions
• Possible DEF system warnings

BMW DTC P221C causes

The common causes of DTC P221C on a BMW include:

• Defective reductant heater ‘B’
• Wiring or connector issues in the reductant heater circuit
• Faulty powertrain control module (PCM)

BMW DTC P221C seriousness

While DTC P221C may not cause immediate drivability issues, it is essential to address this fault promptly to ensure proper emission control and overall vehicle performance. Ignoring this code can lead to increased emissions and potential long-term damage to the emission control system.

How to diagnose DTC P221C on BMW

To diagnose DTC P221C on a BMW, a mechanic would typically perform the following steps:

1. Use a diagnostic scanner to retrieve the trouble codes stored in the vehicle’s PCM
2. Inspect the reductant heater ‘B’ and its circuit for any visible damage or corrosion
3. Check the wiring and connectors related to the reductant heater for continuity and proper connection
4. Test the reductant heater ‘B’ for proper resistance and functionality
5. Verify the PCM operation and communication with the reductant heater

How to fix DTC P221C on BMW

To fix DTC P221C on a BMW, the following steps may be taken:

1. Replace the faulty reductant heater ‘B’ if it is determined to be defective
2. Repair any damaged wiring or connectors in the reductant heater circuit
3. If the PCM is faulty, it may need to be reprogrammed or replaced
4. Clear the trouble codes from the PCM after the repairs are completed

How to erase DTC P221C on BMW

To erase DTC P221C on a BMW, follow these steps:

1. Use a diagnostic scanner to access the vehicle’s PCM
2. Select the option to clear the trouble codes stored in the PCM
3. Follow the on-screen prompts to confirm the code clearing process
4. Once the process is complete, verify that the DTC P221C code has been successfully erased

Recommended tools & DTC Scanners for BMW

Best Diagnostic App for modern BMWs: BimmerLink

Recommended Bluetooth adapter for Bimmerlink: OBDLink CX

Cable adapter for Bimmerlink: Enet Cable USB Type C

For older BMWs we recommend: Autel AutoLink AL319 (2024 version)

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

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