P0373–P0378 Timing Reference High Resolution Signal A Intermittent/Erratic Pulses
The fault comes and goes, which points at a connection that only breaks under vibration, heat or load.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P0373 | Timing Reference High Resolution Signal A Intermittent/Erratic Pulses | Investigate soon |
P0378 | Timing Reference High Resolution Signal B Intermittent/Erratic Pulses | Investigate soon |
The definition
P0373: Timing Reference High Resolution Signal A Intermittent/Erratic Pulses.
P0373 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.
What to check first
Cheapest and fastest checks first:
- Read the freeze-frame data stored with the fault - engine speed, load and temperature at the moment it logged tell you whether this happens cold, hot or under load.
- Check the connector at the part for corrosion, and that it is fully seated.
- Clear the code and see whether it returns, and under what conditions.
What actually causes this on a VAG
The ECU is getting the engine-position signal, but it is unstable - it comes and goes, or the spacing between pulses does not make sense. Faults like this typically show as an occasional stumble, a warning light that clears itself, or a car that cuts out and then restarts perfectly. Because the fault is not present when you look at the car, the trick is working out what it correlates with: heat, bumps, or a particular manoeuvre. This is a generic industry code rather than VAG's own wording, so read the fault with software that shows the manufacturer text as well - it will name the sensor your engine actually has.
Most likely causes, in order
- A loose sensor or a slack mounting bolt. If the sensor can move even slightly, the gap to the wheel changes as the engine rocks and the signal wanders. Check it is fully seated and the bolt is tight. It is the quickest thing to rule out and it costs nothing.
- Wiring or connector fault that only shows up hot or over bumps. Oil in the plug, a corroded pin, or a wire chafing on a bracket all produce exactly this pattern. If you can, watch engine RPM in live data while wiggling the loom and connector with the engine idling - a momentary drop-out is the fault happening in front of you.
- Sensor failing with heat. A well-known pattern on VAG engines: the car runs fine cold, then stumbles or cuts out once thoroughly warmed through, and restarts after standing for a while. If the fault clearly follows temperature and the wiring is sound, the sensor is the likely culprit and it is not usually an expensive part.
- A damaged reluctor ring, flexplate or driveplate. The wheel this sensor reads turns with the crankshaft. If its teeth are damaged, or a cracked flexplate lets the ring move as the engine loads and unloads, the pulse spacing genuinely does become erratic and no sensor will cure it. This is the least common cause here and the most involved to confirm, so leave it until the sensor, plug and loom have all been checked. Be more suspicious of it if the code arrived alongside a rattle or knock from the bellhousing area.
Worth knowing: Two things not to do on this code. First, do not let anyone sell you a timing belt or chain job on the strength of P0373 alone. The wheel this sensor reads turns with the crankshaft, so belt or chain condition cannot corrupt this signal. What points at timing is a crankshaft-to-camshaft correlation code - P0016 or P0017 - stored alongside it. If those are present, the timing is the job and this is a symptom of it. If they are not, this is a sensor, wiring or reluctor problem and the timing is a red herring that costs four figures to chase. Second, do not fit a second sensor because the first one did not fix it. If a new sensor changed nothing, the answer is in the plug, the loom or the wheel, and a third sensor will not change that either.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
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Common questions
What does P0373 mean?
P0373 means Timing Reference High Resolution Signal A Intermittent/Erratic Pulses. The fault comes and goes, which points at a connection that only breaks under vibration, heat or load.
Can I drive with P0373?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.