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OBD-II Code

P2078

Severity

Not yet reviewed

Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.

Can you drive it

We cannot say

Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.

Indicative cost (USD)

$90–$650

From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.

P2078 is the bank-2 intake-manifold tuning valve position sensor 'circuit low' fault - the position-sensor signal voltage has fallen below the lower electrical threshold, typically below 0.2V on a 5V-referenced potentiometer.

How a shop works this

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.

  1. Note every code that is set, not just this one.

    Codes that appear together usually narrow the cause faster than any one of them read alone.

  2. Read the freeze frame — the conditions the fault was recorded under.

    Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.

  3. Confirm the fault is current rather than history.

    Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.

  4. Then follow the diagnostic notes further down this page, in the order they are written.

    They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.

If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.

Common symptoms

  • Check engine light
Read the full diagnostic procedureP2078 is the bank-2 intake-manifold tuning valve position sensor 'circuit low' fault - the position-sensor signal voltage has fallen below the lower…

P2078 is the bank-2 intake-manifold tuning valve position sensor 'circuit low' fault - the position-sensor signal voltage has fallen below the lower electrical threshold, typically below 0.2V on a 5V-referenced potentiometer. Unlike P2077 (range/performance, where the sensor reports an implausible value), P2078 is a hard electrical fault: the wire is shorted to ground, the sensor's wiper has lost contact with its track, or the harness is broken.

Cheapest-first ladder

  1. Disconnect the sensor and read signal-wire voltage at the connector KOEO - a stuck-low signal with the sensor unplugged means the harness is shorted to ground between the sensor and the ECU; a normal 2.5V floating reading with the sensor unplugged means the sensor itself is the failure.
  2. Visually inspect the sensor housing for cracking or moisture intrusion - IMRC position sensors mounted on top of intake manifolds get heat-cycled and crack open over time.
  3. Confirm 5V reference and ground at the sensor connector - a shared 5V bus with another shorted sensor can drag this signal down too. Expensive-misdiagnosis trap: replacing the IMRC actuator-with-integrated-sensor assembly when the standalone sensor or a $50 harness repair would have fixed it.
Vehicle-specific patterns2008-2013 Audi / VW 3.6L VR6 FSI in Touareg / Q7 / Passat throws P2078 from a failed intake-flap position sensor on the bank-2 side - VW issued a par…
  • 2008-2013Audi / VW 3.6L VR6 FSI in Touareg / Q7 / Passat throws P2078 from a failed intake-flap position sensor on the bank-2 side - VW issued a part-number update on the motor/sensor assembly.
  • 2006-2010Mercedes-Benz M272 V6 (C350, E350, R350) throws P2078 from a known intake-manifold runner-flap sensor fault (sometimes combined with the larger balance-shaft gear wear issue).
  • 2009-2014Hyundai Genesis sedan 3.8L (Lambda II V6) throws P2078 from a runner-control sensor that loses signal as the connector ages.
  • 2007-2013Cadillac STS / CTS with the 3.6L LLT throws P2078 from harness chafing near the throttle body.

Estimated repair$90 to $650

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