P2607: Intake Air Heater B Circuit Low
What to do
Expect poorer cold starting and more white smoke. Not damaging in itself, so getting to a workshop is fine.
One safety point worth passing on: if a fuse or fusible link for this circuit has blown, it must not be replaced with a bigger one. This heater draws a current comparable to a starter motor, and that fuse protects a heavy cable running across a hot engine. A blown one means something is shorting, and finding what is the repair — a larger fuse just removes the protection.
What this code means
The second intake air heater's control circuit reads below its valid range — normally a short to ground, or a driver output in the module that has failed low.
A short to ground on this circuit is worth taking seriously in a way that most low-circuit codes are not, because of what the circuit is connected to. The control side switches a relay, and the relay switches something drawing tens of amperes. A short on the control wire is an ordinary repair; a short on the supply side of the relay is a heavy cable trying to earth itself, which is a fire risk rather than an inconvenience. The fuse or fusible link protecting that cable is there for exactly this reason, and one that has blown should never simply be replaced with a larger one.
The cabling runs across the top of a hot engine to reach the manifold, so chafing against a bracket or a heat shield is the usual mechanism.
The driveability consequence is the same as the rest of the family: colder starting, more smoke, rougher running until warm.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Damaged wiring harness · moderate
- Failed intake air heater relay · moderate
Less common
- Control module driver failure · specialist
- Blown fuse supplying the heater circuit · easy
Symptoms
Components involved
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.
Community experience
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