P20CB - Exhaust Aftertreatment Fuel Injector Control Circuit/Open
The P20CB code indicates a problem in the control circuit of the exhaust aftertreatment fuel injector, which is used to inject fuel into the diesel particulate filter (DPF) for regeneration. The powertrain control module (PCM) has detected an open or short circuit in the injector's control circuit, preventing proper operation. This can lead to incomplete DPF regeneration, increased emissions, and potential damage to the exhaust system.
1. Most Common Causes
- Faulty exhaust aftertreatment fuel injector
- Open or shorted wiring in the injector control circuit
- Corroded or damaged connector at the injector
- Failed PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Increased exhaust emissions
- Possible DPF clogging and reduced engine performance
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes.
Step 2: Visually inspect the injector and its wiring harness for damage, corrosion, or loose connections.
Step 3: Test the injector resistance with a multimeter (specs vary; typically 0.5-2 ohms).
Step 4: Check for voltage and ground at the injector connector with the ignition on.
Step 5: If wiring and injector are okay, test the PCM output circuit for continuity and shorts.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can lead to DPF clogging and costly repairs. Short trips may be possible, but the vehicle should be diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on whether the injector needs replacement and labor rates. Wiring repairs are usually cheaper.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.