P1429 Glow Plug Circuit Malfunction (Nissan/Infiniti)
The P1429 code indicates a fault in the primary glow plug circuit, which is controlled by the EGI (Electronic Gasoline Injection) module. This code is specific to Nissan and Infiniti diesel vehicles and is triggered when the control module detects an abnormal voltage or current in the glow plug heating circuit during cold starts. The glow plug system is critical for starting and reducing emissions in diesel engines, as it heats the combustion chambers to facilitate fuel ignition.
01. Most Common Causes
- Open or shorted glow plug
- Faulty glow plug relay
- Damaged wiring or corroded connections in the glow plug circuit
- Internal EGI/ECU failure affecting glow plug control
- Blown fuse in the glow plug circuit
02. Symptoms You Will Notice
- Hard starting, especially in cold weather
- Check Engine Light illuminated
- Excessive smoke on startup
- Rough idle or misfire until engine warms up
03. Step-by-Step Diagnosis
Scan for codes and verify P1429 is present.
Inspect glow plug fuses and replace if blown.
Test each glow plug for resistance; replace any that are open or shorted.
Check glow plug relay operation and wiring for damage or corrosion.
If all else is good, test the EGI/ECU for proper glow plug control signals.
1. Frequently Asked Questions
Is it safe to drive?▼
Driving with P1429 is not recommended, especially in cold weather, as it can cause hard starting, increased emissions, and potential engine damage from incomplete combustion.
How much does it cost to fix?▼
Repair costs typically range from $200 to $600, depending on whether the issue is a simple glow plug replacement or a more complex ECU repair.