OBD-II Code P1406 — What It Means & How to Fix It

What Does This Error Mean?

P1406 is a GM-specific code indicating that the EGR (Exhaust Gas Recirculation) valve pintle position is out of range. The EGR valve on these GM vehicles has a built-in position sensor (pintle sensor) that tells the PCM exactly how far open the valve is. When the pintle position reading is higher or lower than expected, P1406 is set. This is very common on GM 3.1L, 3.4L, and 3.8L engines from the 1990s and 2000s.

Affected Models

Very common in Chevrolet Malibu and Monte Carlo with 3.1L V6
Common in Buick Century and Regal with 3.8L V6
Common in Pontiac Grand Prix and Grand Am
Common in Oldsmobile Cutlass Supreme and Intrigue

Common Causes

Faulty EGR valve with a worn or failed internal pintle position sensor
Heavy carbon buildup holding the EGR valve pintle open or closed
Broken or corroded wiring at the EGR valve connector
Damaged EGR valve pintle stem preventing accurate position reporting
Vacuum supply issue on vacuum-controlled EGR systems

How to Fix It

Locate the EGR valve — on GM 3.1L and 3.8L engines it is typically on the intake manifold and easy to access.

The valve has an electrical connector (for the pintle sensor) and either a vacuum line or direct mounting to the exhaust gas passage.
Inspect the EGR valve connector for corrosion or damaged pins. Clean the connector with electrical contact cleaner.

A dirty or corroded connector is a quick fix that sometimes resolves P1406 without replacing the valve.
Remove the EGR valve and inspect the pintle (the needle-like stem in the center). Check for heavy carbon deposits.

Carbon can hold the pintle in a partially open or closed position. Clean it with EGR cleaner or carburetor cleaner.
If the pintle is cracked, bent, or the valve body is damaged, replace the EGR valve assembly.

The pintle position sensor is integral to the GM EGR valve — you cannot replace just the sensor.
After replacement or cleaning, reinstall the valve, clear codes, and perform a complete drive cycle.

The EGR monitor requires a warm engine at operating temperature to run its test and confirm the repair.

When to Call a Professional

EGR valve replacement on GM 3.1L–3.8L engines is a common DIY repair. OEM or quality aftermarket EGR valves cost $50 to $150. Professional installation adds $80 to $150 labor. Carbon buildup cleaning is worth attempting before replacing the valve.

Frequently Asked Questions

Can I clean the EGR valve instead of replacing it?

Yes, and it is worth trying first. Remove the valve and spray carburetor cleaner or dedicated EGR cleaner into the passages. Work the pintle manually and let it soak to loosen carbon deposits. If the pintle moves freely after cleaning and the sensor reads correctly, you may not need a new valve.

Is P1406 unique to older GM V6 engines?

It is most commonly associated with GM 3.1L, 3.4L, and 3.8L engines from the mid-1990s to mid-2000s. These engines used an EGR valve with an integrated position sensor that is prone to carbon buildup. Newer engines use different EGR designs that do not typically generate P1406.

Can P1406 cause rough idle or hesitation?

Yes. If the EGR valve is stuck open due to carbon buildup, it allows exhaust gas into the intake at idle when it should be closed. This creates a rough idle, stalling, and hesitation. A stuck-open EGR valve at idle is one of the most noticeable symptoms of P1406.