Glow Plug Circuit High Side, High Input
19 articles · 3 makes affected
What is P1399?
P1399 indicates a problem with the glow plug circuit's high side, specifically detecting voltage that's too high. This is a powertrain code that affects diesel engine starting systems, and while not immediately disabling, it can cause hard starting in cold weather. Based on real data, this code appears most frequently in Honda Accord, Chevrolet Spark, and Ford Edge models.
Common Causes
- ●Faulty glow plug(s) (most common cause based on diagnostic patterns)
- ●Wiring harness issues or short to power in the glow plug circuit
- ●Malfunctioning glow plug control module or relay
Symptoms You May Notice
- ●Illuminated check engine light (universally reported)
- ●Hard starting or extended cranking, especially in cold conditions
- ●Possible engine misfires, as noted in some Honda Accord cases where owners reported misfires on cylinders 1 and 2
How to Fix It
- ●Replace faulty glow plug(s) ($50-$150 per plug, moderate difficulty)
- ●Repair or replace damaged wiring in the glow plug circuit ($150-$400, moderate difficulty)
- ●Replace glow plug control module or relay ($200-$500, moderate difficulty)
Owner Statistics
Based on 15,560 real owner discussions • 1227 confirmed solutions
About This Data
Statistics are aggregated from real owner discussions on Reddit, automotive forums, and YouTube comments. All data is anonymized and represents actual repair experiences reported by vehicle owners.
Frequently Appears With
These codes often appear together in owner reports. Check these if you see P1399.
Based on analysis of 26 owner reports where multiple codes appeared together.