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Engine

Problems of the glow plugs: symptoms, cost and affected models

We have documented 3 faults of the glow plugs in 2 engines and 1 car, affecting 3 models of car in our database. The most important by severity and frequency: short circuit in the auxiliary PTC cabin heater with fire risk (Land Rover Freelander 2), glow plugs seize and snap when removed on the OM611 (2.2 CDI (OM646)) and premature glow plug failure on the 2.8 D-4D (2.4 / 2.8 D-4D (GD)).

Documented faults
3
1 of high or critical severity
Engines
2
with at least one fault on this part
Affected models
3
car generations in our database
Garage repair
No data
No reliable published costs

How we work

How it works and why it fails

Glow plugs

Glow plugs, or preheating plugs, heat the combustion chamber of diesel engines so they start when cold. They are controlled by an ECU or relay, and a fault is signalled by the glow plug warning light on the dashboard.

What to do

If a diesel starts badly when cold, smokes white on start-up or the glow plug light flashes, check the glow plugs and their control module. Replacing them in time stops them seizing in the cylinder head, where removing a broken one is an expensive repair.

General explanation by MotorFiable. The specific faults of each engine and car, with their sources, are on the linked pages.

Common symptoms

The symptoms that come up most often in the documented faults of the glow plugs. Open each one to see what other faults cause it.

Problems of the glow plugs by engine

From most to least important (severity × frequency). Each page details the affected versions and years, symptoms, cost and how to check for it.

  1. 1Medium severityFrequency: Occasional2.2 CDI (OM646)Glow plugs seize and snap when removed on the OM611On Mercedes OM611, OM612 and OM613 diesels, glow plugs can break when loosened, because they stick in the cylinder head through carbon and rust. Hella published a bulletin with a specific procedure to avoid this.
  2. 2Low severityFrequency: Rare2.4 / 2.8 D-4D (GD)Premature glow plug failure on the 2.8 D-4DOn the Land Cruiser 150 with the 2.8 D-4D, AutoBild points out that what tends to fail early is the glow plugs, which also often resist removal and make the labour more expensive.

Engines with faults of the glow plugs

Problems of the glow plugs by car

Faults documented on specific cars, which occur with any engine. From most to least important.

  1. 1Critical severityFrequency: OccasionalLand Rover Freelander 2Short circuit in the auxiliary PTC cabin heater with fire riskBetween 2008 and 2015 there were three British recalls for a possible short circuit in the auxiliary PTC cabin heater of the Freelander 2. Typically the battery is drained and the car will not start; it can also produce a smell of melting components and, in extreme cases, a fire.

Frequently asked questions

Which engines have the most faults of the glow plugs?

By severity and frequency, the 2.2 CDI (OM646) (glow plugs seize and snap when removed on the OM611, medium severity) and the 2.4 / 2.8 D-4D (GD) (premature glow plug failure on the 2.8 D-4D, low severity).

Which cars have problems of the glow plugs?

Among those we have analysed: Land Rover Freelander 2 (short circuit in the auxiliary PTC cabin heater with fire risk).

What symptoms does a fault of the glow plugs cause?

The most frequently cited in the documented faults: glow plug warning light flashing, hard starting or engine will not start, battery goes flat while the car is parked and burning smell.