What causes GM code 16?

Weak battery or failing alternator with low charging voltage Loose or corroded battery cables and engine grounds Worn alternator belt slipping under load On DIS models a direct ignition system circuit fault setting the same code

How do I fix GM code 16?

Measure battery voltage and charging voltage under load with a meter Clean and tighten battery terminals and engine ground straps Test alternator output before replacing any ignition parts On DIS models check ignition module power and ground feeds Clear the code and retest after the charging system holds steady voltage

16 System Voltage Too Low

Q: What does GM code 16 mean?

GM code 16. System Voltage Too Low. Applies to 1984-1995 GM cars and C/K trucks with DIS ignition, Beretta, Lumina.

Make: GM (1982-1995)
Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: 1984-1995 GM cars and C/K trucks with DIS ignition, Beretta, Lumina

How to read it

Code 16 reads as 1 flash, pause, 6 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

What does GM code 16 mean?

16. System Voltage Too Low. This code sets when your vehicle computer detects system voltage too low.

Common causes of 16

Weak battery or failing alternator with low charging voltage
Loose or corroded battery cables and engine grounds
Worn alternator belt slipping under load
On DIS models a direct ignition system circuit fault setting the same code

How to fix 16

Measure battery voltage and charging voltage under load with a meter
Clean and tighten battery terminals and engine ground straps
Test alternator output before replacing any ignition parts
On DIS models check ignition module power and ground feeds
Clear the code and retest after the charging system holds steady voltage