🚗 Error Code P066B – Glow Plug Cylinder #1
❓ What Does It Mean?
This diagnostic trouble code (DTC) is generic and applies to many OBD-II vehicles (Jeep, Chrysler, BMW, Toyota, Volkswagen, Dodge, Ram, Ford, Chevrolet, Mazda, etc.).
The P066B code indicates that the Powertrain Control Module (PCM) has detected excessively high voltage in the control circuit of the glow plug for cylinder #1.
🔍 Reminder: Diesel engines use glow plugs to increase cylinder temperature and ensure proper starting, as they do not operate with sparks like gasoline engines.
⚠ Severity of the Problem
A P066B code can cause significant driving issues. It is therefore urgent to diagnose and resolve the problem quickly.
🔎 Symptoms of Code P066B
✅ Excessive black smoke from the exhaust ✅ Driving difficulties (hesitation, stumbling during acceleration) ✅ Delayed engine starting ✅ Increased fuel consumption ✅ Recorded misfire codes
🛠 Possible Causes
🔧 Faulty glow plug 🔧 Open or shorted control circuit 🔧 Loose or damaged glow plug connector 🔧 Faulty glow plug timer or control module
🏁 Troubleshooting Code P066B
1️⃣ Visual Inspection 🔍
🔹 Check all glow plug cables and connectors 🔹 Look for any damaged, melted, or disconnected wires
2️⃣ Reading Error Codes 💻
🔹 Use an OBD-II scanner to retrieve stored error codes 🔹 Note freeze frame data for analysis 🔹 Clear the codes and test the vehicle to see if the code returns
3️⃣ Testing Glow Plugs 🔥
🔹 Remove the plug and apply battery voltage 🔹 A functioning plug will become glowing red 🔹 If it does not heat up, test its resistance with a voltmeter (DVOM)
⚠ Caution: Risk of burns or fire during this test!
4️⃣ Checking Power Supply ⚡
🔹 Use a DVOM to test voltage at the glow plug connector 🔹 If no voltage is present, check the timer or control module 🔹 Test all associated fuses and relays
5️⃣ Control Circuit Check 🔄
🔹 Verify if the PCM is sending the correct voltage 🔹 If voltage is detected at the PCM output, suspect faulty wiring
🚀 Conclusion
Do not underestimate this code! A P066B can be caused by a faulty glow plug affecting the control circuit. Always verify the correct cylinder before performing in-depth diagnostics.
By following these steps, you can identify the source of the problem and resolve it effectively. 🔧🚗