Exhaust Aftertreatment Glow Plug Circuit High
The P26A2 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the exhaust aftertreatment glow plug circuit. This circuit is used to heat the diesel particulate filter (DPF) or selective catalytic reduction (SCR) system to aid in regeneration and reduce emissions. A high voltage reading suggests a short to power, faulty glow plug, or wiring issue, which can prevent proper exhaust treatment and lead to increased emissions or DPF clogging.
01. Most Common Causes
- Short to power in the glow plug circuit wiring
- Faulty exhaust aftertreatment glow plug
- Corroded or damaged connector
- PCM internal failure (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: Use a scan tool to retrieve freeze frame data and confirm the code.
Step 2: Visually inspect the glow plug wiring and connector for damage, corrosion, or shorts.
Step 3: Measure resistance of the glow plug; compare to manufacturer specs (typically 0.5-2 ohms).
Step 4: Check for voltage at the glow plug connector with key on; should be battery voltage. If higher, trace short to power.
Step 5: If wiring and plug are okay, test the PCM output circuit for shorts or replace PCM if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can lead to DPF clogging and increased emissions. Short trips may be okay, but have it diagnosed soon.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, but could be higher if the glow plug or PCM needs replacement.