P2597: Turbocharger Speed Sensor B Circuit Intermittent
What to do
The car will often feel normal, with occasional flat spots at higher speeds or a light that comes and goes.
Note when it happens. A fault that appears after a long climb or a sustained fast run and clears once things cool points at heat affecting a connector or the wiring — a small job.
Ask for one check regardless: play in the turbocharger shaft. This sensor reads the compressor blades going past, so worn bearings letting the shaft wobble give exactly this jumpy signal. It takes a couple of minutes and distinguishes a wiring fault from a turbocharger beginning to fail.
Worth investigating even if you have not noticed anything wrong. On a car with two turbochargers the second one may only work hard at higher speeds, so a stored fault with no symptom in normal driving often just means you have not been driving where the problem lives.
What this code means
The second turbocharger's speed signal drops out or jumps rather than tracking smoothly, and recovers.
The two explanations given at P2582 both apply. Heat cycling works connectors loose and opens cracks in hardened insulation that close again as things cool, so a fault that appears after a long climb or a sustained fast run and clears afterwards is pointing at a connection rather than at the turbocharger. A genuinely erratic shaft is the other, and it is the one that matters: these sensors count the compressor blades passing, so worn bearings letting the shaft move produce a jumping speed signal. That makes an intermittent speed code an unusually direct early report of a turbocharger starting to fail, and checking for shaft play takes minutes.
What is worth adding on a twin-turbo engine is that the second unit is the harder one to catch this way. On a sequential system it only works hard at higher engine speeds, so the conditions that expose the fault are the ones least likely to occur on the way to a workshop — and the symptom is confined to the top of the rev range, where a driver may not go often. A code stored intermittently on the second turbocharger, with no complaint at all in ordinary driving, is therefore worth investigating rather than clearing, because the absence of a symptom mostly reflects where the car has been driven.
Likely causes
Start here
- Intermittent wiring fault · moderate
- Corroded or loose connector · easy
- Heat damage to sensor or wiring · moderate
Less common
- Worn turbocharger bearings · specialist
- Faulty turbocharger speed sensor · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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