P0338–P0388 Crankshaft Position Sensor A Circuit High
The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.
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 |
|---|---|---|
P0338 | Crankshaft Position Sensor A Circuit High | Investigate soon |
P0388 | Crankshaft Position Sensor B Circuit High | Investigate soon |
The definition
P0338: Crankshaft Position Sensor A Circuit High.
P0338 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:
- Unplug the sensor and check whether the signal falls. If it stays high, suspect the wiring rather than the sensor.
- Check the earth path - a missing earth makes a sensor read high.
What actually causes this on a VAG
The crankshaft position sensor's signal line is sitting up near supply voltage rather than pulsing as the engine turns. In practice that usually means the circuit is broken somewhere between the ECU and the sensor. Without a crankshaft signal the ECU cannot time ignition or injection, so this normally shows up as an engine that spins over healthily but never fires.
Most likely causes, in order
- Connector not properly latched, or a pin pushed back. The connector lives in a hot, oily and constantly vibrating place. A half-seated plug or a terminal that has backed out of the housing behaves exactly like a snapped wire. Unclip it, check each terminal sits firmly, and give each wire a gentle tug at the rear of the plug.
- Broken wire between sensor and ECU. An open circuit anywhere along the run gives this reading. Flex the loom along its length by hand, particularly where it crosses from body to engine and where it passes any bracket or heat shield.
- Sensor failed open internally. Perfectly possible, and it looks identical to a broken wire until someone measures at the sensor's own connector. Inspecting the sensor itself tells you nothing.
- Missing supply or earth to the sensor. Some of these sensors need a feed and an earth as well as the signal wire, so losing either leaves the signal line dead. Worth having checked before a new sensor is fitted, since a fresh part will behave identically.
Worth knowing: Check the plug is fully clipped home before spending anything. If the car has just been in for clutch, gearbox, starter motor or timing work, the sensor connector is a prime suspect for having been disturbed, and reseating it is free.
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 P0338 mean?
P0338 means Crankshaft Position Sensor A Circuit High. The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.
Can I drive with P0338?
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.