What it means
The aftertreatment glow plug current is above expected. Internal short reduces resistance. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The aftertreatment glow plug heats the exhaust on some diesels to support ignition of injected fuel during DPF regeneration. P26A2 means the monitored plug current is above its expected range, which can point to an internally shorted element or an abnormal supply voltage.
Common causes
Most likely first.
- Internal short in the glow plug element
- Supply voltage above specification
- Connector pins corroded - high contact resistance
Symptoms
- Glow plug warning light on (often orange coil symbol)
- Hard cold start or no start in cold weather
- White smoke from exhaust during warm-up
How to diagnose it
- Check freeze-frame data and commanded glow plug current to establish whether the high reading is continuous or occurs only during heater operation.
- Inspect the plug connector and harness for chafing, damaged insulation, moisture, or corroded terminals.
- Check supply voltage at the glow plug under load against the manufacturer's specification before condemning the element.
- Measure element resistance with power isolated according to the manufacturer's procedure and compare it with the specified range.
- If the plug tests correctly, inspect relay output and wiring for an unintended power feed or intermittent short while monitoring the circuit.
Common fixes
- Secure or clean a serviceable connector with a poor contact.
- Repair chafed wiring or an unintended power connection.
- Replace the glow plug if its element tests as internally shorted.
- Repair a relay or supply fault if voltage is outside specification.
Can I keep driving?
Driving gently is generally possible if the engine runs normally, but the heater fault can prevent reliable cold starting and DPF regeneration. Avoid repeated short trips and get persistent white smoke or a DPF warning checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.