Exhaust Aftertreatment Glow Plug Circuit Low
The P26A1 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the exhaust aftertreatment glow plug circuit. This circuit is responsible for heating the exhaust aftertreatment system, typically a diesel particulate filter (DPF) or selective catalytic reduction (SCR) system, to aid in regeneration and reduce emissions. A low voltage reading suggests a short to ground, open circuit, or faulty glow plug, which can prevent proper exhaust treatment and lead to increased emissions.
01. Most Common Causes
- Faulty exhaust aftertreatment glow plug
- Open or shorted wiring in the glow plug circuit
- Corroded or damaged connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel efficiency
- Increased exhaust emissions
- Possible DPF regeneration issues
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the glow plug wiring and connectors for damage or corrosion.
Step 3: Measure resistance of the glow plug; compare to specifications.
Step 4: Check voltage at the glow plug connector with the circuit active.
Step 5: Test the PCM output for the glow plug circuit.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive short distances, but prolonged driving may cause DPF clogging and reduced performance. Have it diagnosed promptly.
How much does it cost to fix?▼
Typical repair costs range from $50 to $150 for parts and labor, depending on the cause and vehicle.