P2672: Injection Pump Timing Offset
What to do
Expect the engine to be noisier than usual — a harder, more rattly note — along with smoke, poorer economy and less power. It is not immediately damaging, but it should not be left, because badly timed combustion is hard on pistons and bearings over time.
Before anyone quotes for an injection pump, ask for two much cheaper things to be checked, in this order:
- The fuel filter and fuel supply. Many pumps use their own internal fuel pressure to advance timing, so a restricted filter genuinely retards injection timing and sets this code. It costs very little and takes minutes.
- The mechanical timing — the belt or chain, its tensioner, and the pump drive. If the belt or chain has ever been replaced, say so. A tooth out at that point leaves the engine module quietly correcting for it for years until it runs out of adjustment, which is exactly what this code is.
An injection pump is one of the most expensive parts on a diesel, and it is often replaced for a code that a filter or a timing correction would have cleared. Ask what has been ruled out.
What this code means
The correction the module applies to injection timing has drifted beyond the range it is allowed to use. The pump is delivering fuel at a moment far enough from the commanded one that the module can no longer trim the difference away.
Injection timing on a diesel is not a setting so much as a running negotiation. When fuel enters relative to the piston's position governs almost everything that matters: how much of it burns, how hard the pressure rise is, how much soot and how much oxides of nitrogen come out, and how the engine sounds. The module commands a moment, watches the result, and holds a learned offset to account for the pump's own tolerances, wear and temperature. This code says that learned offset has run out of room.
Two very different things produce it, and the order to check them in is the reverse of the intuitive one.
Mechanical timing is the first, and it is the cheaper answer. A timing belt or chain fitted a tooth out, a stretched chain, a worn tensioner or a pump drive that has slipped moves the whole relationship between crankshaft and pump. The module then spends its entire offset compensating for an assembly error — and because it compensates successfully at first, the engine can run acceptably for a long time before the offset finally runs out. A vehicle that has had timing work at some point in its history and set this code later is that until proven otherwise, and it is worth asking whether the belt or chain has ever been touched.
Wear inside the pump is the second — the metering assembly, the timing advance mechanism, the internal transfer pressure that many pumps use to advance timing hydraulically. Low transfer pressure retards timing exactly as though the pump were mistimed, and it is caused by wear, by a restricted supply, or simply by a blocked fuel filter.
So the filter and the fuel supply come before the pump. A restricted filter is a genuine cause of this code, costs almost nothing, and is checked in minutes — while a pump is one of the most expensive parts on a diesel engine and is very often replaced on the strength of a code that a filter would have cleared.
Likely causes
Start here
- Restricted fuel filter · easy
- Timing belt or chain fitted incorrectly · specialist
- Worn injection pump metering assembly · specialist
Less common
- Stretched timing chain · specialist
- Low fuel supply pressure · moderate
- Air drawn into the fuel supply · moderate
Symptoms
Components involved
Information, not instruction
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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.
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