Glow Plug Light (Diesel) on a Volkswagen Up
This is usually informational. Address it at your convenience.
What the Glow Plug Light (Diesel) Means on a Volkswagen Up
The glow-plug light on your diesel Volkswagen Up is your cue to wait a couple of seconds before starting in cold weather. A flashing light after the engine is running, however, indicates a fault the ECU wants checked.
How Urgent Is the Glow Plug Light (Diesel)?
In terms of priority, treat this as a low concern on your Volkswagen Up. The single most useful thing you can observe is whether the Glow Plug Light (Diesel) is steady or blinking: a steady light generally allows a careful drive to a safe location or a workshop, whereas a flashing light signals an active fault that can cause damage if you continue. Pay attention to changes in how the Volkswagen Up drives, sounds, or smells, since those symptoms sharpen the diagnosis considerably.
Common Symptoms Alongside the Glow Plug Light (Diesel)
The Glow Plug Light (Diesel) on your Volkswagen Up is one data point, and the symptoms around it are the rest of the story. Perhaps the engine feels different, a gauge reads unusually, or the car behaves normally but the symbol simply will not clear. Note everything you observe, because the pattern of symptoms on the Volkswagen Up is exactly what turns a vague warning into a specific, fixable diagnosis.
- Light on briefly at cold start (normal)
- Flashing light after warm-up (fault)
- Hard starting when cold
- Rough running or white smoke on cold mornings
What Causes the Glow Plug Light (Diesel) to Come On?
The Glow Plug Light (Diesel) on the Volkswagen Up can be triggered by several conditions, and experienced technicians work through them from most to least likely. Some causes are trivial and cost almost nothing to correct, while others require replacing a sensor or component. The list below reflects what actually turns this light on in the real world, so you can gauge whether you are likely facing a quick fix or a workshop visit.
- Normal pre-heat cycle (steady, brief)
- One or more failed glow plugs
- Glow plug relay fault
- Crankshaft/camshaft sensor issue
- Related engine management fault
How to Fix the Glow Plug Light (Diesel) on a Volkswagen Up
Fixing the Glow Plug Light (Diesel) on a Volkswagen Up is methodical, not mysterious. Start with the quick, no-cost checks, then let the vehicle's own trouble codes guide you toward the specific system at fault. The ordered steps here are designed so that by the time you (or your technician) reach the more involved work, you have already eliminated the easy explanations.
- At cold start, wait for the light to go out before cranking
- If it flashes, scan for glow-plug and engine codes
- Test each glow plug for resistance/continuity
- Replace failed plugs (ideally as a set) and check the relay
- Clear codes and confirm easy cold starts
Is It Safe to Drive With the Glow Plug Light (Diesel) On?
Safe-to-drive depends on judgement, and here is the technician's version for a Volkswagen Up: respect the colour, respect the behaviour. Given this light's low urgency, treat any red or flashing warning as a stop-now signal. If everything feels normal and the light is amber, a short, cautious drive to a garage is typically fine, provided you do not delay the actual diagnosis.
Diagnostic Trouble Codes Linked to the Glow Plug Light (Diesel)
If you scan a Volkswagen Up showing this light, these are the OBD-II trouble codes most commonly associated with it. The code you actually retrieve is what pinpoints the repair.
| Code | Meaning |
|---|---|
P0335 |
Crankshaft Position Sensor Circuit The crankshaft position sensor signal is faulty, which can cause stalling or a no-start condition. |
Professional Mechanic Tips
Hard cold starts plus a flashing glow-plug light on a diesel Volkswagen Up usually means one or more plugs have failed — replace them as a set for even starting.
Do not ignore a flashing glow light; on many diesels it doubles as a general engine fault warning, so scan it rather than guessing.
Frequently Asked Questions
Why is the Glow Plug Light (Diesel) on in my Volkswagen Up?
On a Volkswagen Up, the Glow Plug Light (Diesel) comes on because a monitored value crossed a threshold the car considers abnormal. It could be a simple, inexpensive cause or a genuine fault — the only way to be sure is to scan the vehicle and interpret the codes rather than guess from the symbol alone.
Can I keep driving with the Glow Plug Light (Diesel) on?
For a Volkswagen Up, a steady amber Glow Plug Light (Diesel) with normal driving generally allows a careful trip to a garage. A red or flashing light, or any change in performance, means you should stop and avoid further driving until the fault is identified.
How much does it cost to fix the Glow Plug Light (Diesel) on a Volkswagen Up?
There is no single price for the Glow Plug Light (Diesel) on a Volkswagen Up; it ranges from a no-cost adjustment to a component replacement. The honest way to control cost is to diagnose the exact code before authorising any repair, so you only pay to fix what is actually wrong.
Will the Glow Plug Light (Diesel) reset itself on a Volkswagen Up?
Sometimes the Glow Plug Light (Diesel) on a Volkswagen Up clears on its own once the condition that triggered it no longer exists — for example after several good drive cycles. More often, though, the light stays on until the underlying fault is repaired and the code is cleared, so treat a self-clearing light as a reason to still investigate.