Glow plugs on the Renault Trafic 2017 1.6 dCi are accessible from the top of the engine once the coolant bottle and oil filler are moved aside. No special tools are required - just a quarter-drive 10mm socket and extension.
This procedure is the same for the Vauxhall Vivaro and Nissan Primastar with the same engine. Replace all four as a set at around 80,000 to 100,000 miles.
When You Need This Job
- Long cranking time on cold starts
- Excessive white smoke on cold startup
- Glow plug warning light on the dashboard
- Rough running when cold that improves as the engine warms
Renault Trafic Owner's Bible (also Vivaro)
- Trafic and Vivaro specific faults and service intervals
- The known weak points and what they cost to put right
- Written for the van, by someone who works on them
Instant PDF download · works on phone, tablet or PC · 7-day money-back guarantee
Tools You'll Need
Step-by-Step Guide
Move the coolant bottle and oil filler aside
The coolant bottle is held by a tab - release it and turn it to the side. Remove the cap first to relieve any pressure. Undo the return line by squeezing the two tabs and pull it off. The oil filler cap is a 21mm - undo it and tuck the bottle out of the way.
Locate all four glow plugs
With the coolant bottle moved you can see down to the four glow plug tips. They are in a row along the top of the engine.
Pull off all four electrical connectors
Grab each plastic connector extension and pull it off the glow plug. Use long-nose pliers if they are tight - do not pull by the wire.
Unscrew each plug with the 10mm socket
Feed the quarter-drive 10mm socket down onto the plug head on its extension. Use the quarter-drive ratchet to crack it loose then unscrew by hand. Pull each plug out with fingers or long-nose pliers.
Inspect the old plugs
Corroded bodies and burnt tips confirm they were due for replacement. Plugs 3 and 4 may be harder to access due to wiring - work the socket around the wiring carefully.
Apply anti-seize and fit new plugs
Put a small smear of copper slip or installation grease on the threads of each new plug. Start each one by hand - never use power tools. Tighten firmly with the quarter-drive ratchet.
Refit the electrical connectors
Push each connector down onto its plug until you feel and hear a click confirming it is seated. Use long-nose pliers to push them fully home if needed.
Refit coolant bottle and test
Reconnect the coolant return line, refit the bottle into its holder and replace the oil filler cap. Start the engine - it should start notably quicker than before.
This engine is shared between the Trafic, Vivaro and Primastar. The glow plug procedure is identical on all three.
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More free repair guides on YouTube
Watch on YouTubeWhy Glow Plugs Fail - and How to Tell Which One
A glow plug is a heating element that reaches 1,000 degrees in seconds, every cold morning, for years - and each heat cycle ages the element until one day it goes open-circuit. On the Trafic's 1.6 dCi the plugs typically start failing between 80,000 and 120,000 miles, and they rarely go together: one dies, the van starts a little rougher on cold mornings, then a second goes and winter starts becoming negotiation. White smoke on cold start that clears as the engine warms, lumpy idle for the first minute, and longer cranking below five degrees are the classic one-or-two-plugs-down signature.
Finding the dead one is cheap: a multimeter across each plug reads under an ohm for healthy, open circuit for dead - or a £20 code reader shows glow plug circuit faults per cylinder. Either way, replace all four while you are in there: the survivors have the same heat cycles behind them, and the labour is the job.
Garage vs DIY Cost
| Who does it | Typical price | What you get |
|---|---|---|
| Renault dealer | £180–£320 | Genuine plugs and dealer labour |
| Independent garage | £120–£250 | Quality set fitted |
| DIY | £40–£80 | Four NGK, Bosch or Beru plugs - saving well over half |
Typical UK prices for the 1.6 dCi Trafic. The labour is access and care, not complexity - but the care matters (see the mistakes below).
Genuine Renault vs Aftermarket Plugs
NGK, Bosch and Beru make the glow plugs in everyone's boxes including Renault's; at £10–£20 a plug, the branded aftermarket set is identical hardware for half the dealer counter price. Match the exact specification for your engine code - modern ceramic plugs and older metal ones do not interchange, and the wrong heat rating confuses the glow control module. The £3 unbranded plug is the one place not to economise: cheap plugs can swell at the tip and lock themselves into the head, converting a £60 job into a machine-shop visit.
Common Mistakes on a Glow Plug Change
- Attacking cold seized plugs with a long bar. A snapped glow plug is the single most expensive outcome available in this job. Penetrating oil overnight, warm engine, and torque-limited, patient removal.
- Not clearing the well before unscrewing. Blow the grit out of each plug well first - whatever sits around the plug falls into the cylinder once it comes out.
- Overtightening the new plugs. They are small, hollow and torque to barely finger-plus. Overtightening stretches the shell and guarantees the next removal snaps it.
- Replacing only the dead plug. The other three fail on schedule over the following winters, each time repeating the access labour. All four, always.
- Ignoring the control side. If all four plugs test healthy but the cold-start symptoms persist, the glow control relay/module is the suspect - test before buying another set of plugs.
Related Cold-Start Faults on the dCi
Not every reluctant cold start is glow plugs. Slow, laboured cranking is a battery or earth strap problem - the plugs cannot fix a van that turns over too slowly to fire. Prolonged cranking with healthy plugs and good cranking speed points at fuel pressure falling off overnight (a leaking injector seal or fuel filter housing drawing air). And white smoke that never clears as the engine warms is not glow plugs at all - that is injector or compression territory. The symptom finder separates these before money moves, and the Trafic brake guide covers the newer van's other common job if you run a mixed fleet.
