P263E: Glow Plug Control Module 1 Over Temperature
What to do
Expect this to be a winter problem. With the glow plug system out of action the engine may start perfectly well in mild weather and refuse in the cold, so it is worth fixing before the weather turns rather than when it does.
The one thing to ask for: have the glow plugs themselves measured before the module is replaced. A plug that has failed short is the usual reason one of these modules overheats, and a new module fitted to the plug that cooked the old one fails again — an expensive lesson to learn twice.
Mention any recent starting trouble, however unrelated it seems. Repeated attempts at starting mean repeated heating cycles, which is exactly the condition this module overheats in.
Do not use a can of starting fluid to get a cold diesel going. It is a common shortcut when the glow plugs are not working, and it can do serious mechanical damage to the engine.
What this code means
The glow plug control module has measured its own temperature above the limit it is built to run at, and has shut its outputs down to protect itself.
The name suggests a relay, and it is nothing of the kind — which is the first thing to establish here. An old glow plug relay switched every plug on together for a fixed number of seconds and had no idea what happened next. A modern glow plug control module drives each plug on its own channel, regulates the current flowing in it, and measures that current — which is how it is able to report one open plug, or one shorted plug, by cylinder.
Doing that means handling a very large current inside a small sealed box. A cold glow plug is close to a short circuit: each one draws tens of amps in its first moments and settles to a few, and on a four- or six-cylinder engine those surges are handled together, several times per start, by semiconductors that turn part of that energy into heat. A temperature sensor inside the module is what this code reads.
So the diagnostic point that matters: a module overheats because of what it is driving far more often than because of what it is. A glow plug that has aged into a low resistance, or failed short, forces its channel to carry much more current than it was designed for. Fitting a new module without measuring the plugs puts a new part on the fault that destroyed the old one — the same argument this corpus makes about injector drivers and ignition coil drivers, and it holds here for the same reason.
Two ordinary things make it worse, and both are worth asking about. Glowing continues after the engine has started — on many diesels for up to three minutes, to steady combustion and cut noise and smoke while everything is cold — so the module is working hardest in an engine bay that is already warming up. And repeated failed starts mean repeated glow cycles, which is precisely the condition a car with any other starting problem is in.
What the driver gets is a seasonal fault. With the module shut down there is no pre-heat at all, and a diesel with no working glow plugs starts perfectly in July and not at all in January — so this is often ignored for months and then reported as a sudden failure in the first cold week.
Likely causes
Start here
- Shorted glow plug overloading the module · moderate
- Failed glow plug control module · moderate
Less common
- Incorrect glow plugs fitted · moderate
- Failed control module output driver · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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