Symptom
Booming or droning at low revs in a high gear
A deep boom or drone that fills the cabin at low engine speed in a high gear — the classic case is a light throttle at 1,200 to 1,800 revs — and disappears the moment you change down or accelerate. On an engine with cylinder deactivation this is the sound of it running on half its cylinders, which is exactly what it is meant to do to save fuel, and manufacturers spend real money on active mounts and noise cancellation to hide it. So the question is whether it is new. A car that has always done it quietly and now booms has usually lost the equipment that was masking it, not the deactivation itself.
Also described as: booming noise, droning at low revs, resonance in the cabin, deep drone when cruising, boom at low rpm, cabin booming, صدای بم در دور پایین, غرش در دنده سنگین, retumba a pocas revoluciones, zumbido grave marcha larga, resonancia a bajas vueltas, هدير على الغيار العالي, رنين على دورات منخفضة, صوت مكتوم عند السحب
Some causes mean you should stop driving
14 of the 53 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
On an engine with cylinder deactivation this is the sound of it running on half its cylinders, which is exactly what it is meant to do to save fuel — and manufacturers spend real money on active mounts and noise cancellation to hide it. The classic case is a light throttle at 1,200 to 1,800 revs, and it disappears the moment you change down or accelerate.
So the question is whether it is new. A car that has always done it quietly and now booms has usually lost the equipment that was masking it, not the deactivation itself — an active engine mount that no longer receives its control signal, or the audio system's noise cancellation having stopped working.
That is the diagnostic insight worth carrying, because it points the investigation away from the engine entirely. A perfectly healthy deactivation system will boom audibly if the mounts and the cancellation are not doing their half.
Where the car has no cylinder deactivation, a boom in the same conditions is a resonance being excited — an exhaust mounting that has collapsed so the system touches the body, a heat shield, or a propshaft centre bearing. The test is the same as elsewhere in this group: does it arrive and leave at one point, or grow smoothly?
A drivetrain that is lugging produces it honestly too. An engine held at very low revs in too high a gear boomed before deactivation existed, and a transmission whose shift strategy has changed — after a relearn, a software update, or in an economy drive mode — can produce the complaint with nothing broken.
Report whether it changes with the audio system on or off, because a noise that changes with the stereo is the cancellation rather than the engine.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Light throttle at 1,200 to 1,800 rpm in a high gear, engine has cylinder deactivation | The engine running on half its cylinders — designed behaviour | Note that it clears the instant you change down or accelerate. Read live cylinder deactivation status if the tool shows it. | No repair if it has always done it. If it is new, look at what was masking it rather than at the engine. |
| Was quiet, now booms, nothing else changed | The masking has failed — an active mount without its control signal, or noise cancellation that has stopped | Check whether the boom changes with the audio system on or off, and read active mount control on a scan tool. | Repair the mount control or the cancellation. The deactivation is working correctly. |
| No cylinder deactivation on this engine | A resonance — a collapsed exhaust mounting touching the body, a heat shield, or a propshaft centre bearing | Check exhaust clearances by hand with the system cold, and touch-test heat shields. | Renew the mounting or secure the shield. Cheap and it removes the resonance path. |
| Boom present whenever the engine is lugged in too high a gear | Honest lugging — this predates deactivation and is not a fault | Change down and note that it goes. Consider whether an economy mode or a transmission relearn changed the shift points. | No repair. Adjust the drive mode if the strategy changed after a software update or relearn. |
| Boom with a vibration felt through the seat | Engine mounts rather than sound alone — the mount is passing what it should absorb | Compare in neutral and in gear at a standstill, and inspect the mounts for collapse. | Renew the failed mount. See the rough-in-gear entry, which is the same mechanism at a standstill. |
| Boom that arrives and leaves at one road speed rather than one engine speed | A road-speed resonance rather than an engine one — wheels, tyres or driveline | Hold the same road speed in a different gear. If it follows road speed it is not the engine. | Diagnose as a road-speed noise. See the droning entry in this group. |
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Light throttle at 1,200 to 1,800 rpm in a high gear, engine has cylinder deactivation
- Likely cause
- The engine running on half its cylinders — designed behaviour
- How to confirm it
- Note that it clears the instant you change down or accelerate. Read live cylinder deactivation status if the tool shows it.
- What fixes it
- No repair if it has always done it. If it is new, look at what was masking it rather than at the engine.
-
Was quiet, now booms, nothing else changed
- Likely cause
- The masking has failed — an active mount without its control signal, or noise cancellation that has stopped
- How to confirm it
- Check whether the boom changes with the audio system on or off, and read active mount control on a scan tool.
- What fixes it
- Repair the mount control or the cancellation. The deactivation is working correctly.
-
No cylinder deactivation on this engine
- Likely cause
- A resonance — a collapsed exhaust mounting touching the body, a heat shield, or a propshaft centre bearing
- How to confirm it
- Check exhaust clearances by hand with the system cold, and touch-test heat shields.
- What fixes it
- Renew the mounting or secure the shield. Cheap and it removes the resonance path.
-
Boom present whenever the engine is lugged in too high a gear
- Likely cause
- Honest lugging — this predates deactivation and is not a fault
- How to confirm it
- Change down and note that it goes. Consider whether an economy mode or a transmission relearn changed the shift points.
- What fixes it
- No repair. Adjust the drive mode if the strategy changed after a software update or relearn.
-
Boom with a vibration felt through the seat
- Likely cause
- Engine mounts rather than sound alone — the mount is passing what it should absorb
- How to confirm it
- Compare in neutral and in gear at a standstill, and inspect the mounts for collapse.
- What fixes it
- Renew the failed mount. See the rough-in-gear entry, which is the same mechanism at a standstill.
-
Boom that arrives and leaves at one road speed rather than one engine speed
- Likely cause
- A road-speed resonance rather than an engine one — wheels, tyres or driveline
- How to confirm it
- Hold the same road speed in a different gear. If it follows road speed it is not the engine.
- What fixes it
- Diagnose as a road-speed noise. See the droning entry in this group.
Codes that produce this symptom (53)
Listed with the codes that most typically present this way first — the likeliest place to start.
- P3401 Cylinder 1 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
- P3402 Cylinder 1 Deactivation/Intake Valve Control Circuit Performance Typical of this code Stop driving High
- P3403 Cylinder 1 Deactivation/Intake Valve Control Circuit Low Typical of this code Moderate
- P3404 Cylinder 1 Deactivation/Intake Valve Control Circuit High Typical of this code Moderate
- P3409 Cylinder 2 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
- P340A Deactivation/Intake Valve Control Circuit Bank 1 Typical of this code Moderate
- P340B Deactivation/Intake Valve Control Circuit Bank 2 Typical of this code Moderate
- P3410 Cylinder 2 Deactivation/Intake Valve Control Circuit Performance Typical of this code Stop driving High
- P3411 Cylinder 2 Deactivation/Intake Valve Control Circuit Low Typical of this code Moderate
- P3412 Cylinder 2 Deactivation/Intake Valve Control Circuit High Typical of this code Moderate
- P3417 Cylinder 3 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
- P3418 Cylinder 3 Deactivation/Intake Valve Control Circuit Performance Typical of this code Stop driving High
- P3419 Cylinder 3 Deactivation/Intake Valve Control Circuit Low Typical of this code Moderate
- P341A Deactivation/Intake Valve Control Circuit Performance Bank 1 Typical of this code Stop driving High
- P341B Deactivation/Intake Valve Control Circuit Performance Bank 2 Typical of this code Stop driving High
- P3420 Cylinder 3 Deactivation/Intake Valve Control Circuit High Typical of this code Moderate
- P3425 Cylinder 4 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
- P3426 Cylinder 4 Deactivation/Intake Valve Control Circuit Performance Typical of this code Stop driving High
- P3427 Cylinder 4 Deactivation/Intake Valve Control Circuit Low Typical of this code Moderate
- P3428 Cylinder 4 Deactivation/Intake Valve Control Circuit High Typical of this code Moderate
- P3433 Cylinder 5 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
- P3434 Cylinder 5 Deactivation/Intake Valve Control Circuit Performance Typical of this code Stop driving High
- P3435 Cylinder 5 Deactivation/Intake Valve Control Circuit Low Typical of this code Moderate
- P3436 Cylinder 5 Deactivation/Intake Valve Control Circuit High Typical of this code Moderate
- P3441 Cylinder 6 Deactivation/Intake Valve Control Circuit/Open Typical of this code High
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.
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