What Does P2608 Mean?
The powertrain control module detected an abnormally high voltage in the intake air heater circuit B. This indicates either a short to voltage in the wiring or a failed heater element, commonly found in diesel engines to improve cold-start performance.
Common Causes
35%
Shorted intake air heater element
30%
Wiring harness short to power/voltage
20%
Failed intake air heater relay stuck closed
10%
Corroded or damaged heater connector causing intermittent short
5%
Faulty powertrain control module (PCM)
Diagnostic Steps
1
Step 1: Visually inspect intake air heater B connector and wiring for damage, corrosion, or signs of shorting to power sources
2
Step 2: Disconnect intake air heater B and measure resistance across heater element terminals; compare to manufacturer specifications (typically 0.5-2.0 ohms)
3
Step 3: With heater disconnected, check for voltage at harness connector with ignition on; should read battery voltage briefly then drop to zero
4
Step 4: Test intake air heater relay operation and check relay control circuit from PCM for proper switching
5
Step 5: If all components test normal, verify PCM driver circuit integrity with oscilloscope during heater operation
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The powertrain control module detected an abnormally high voltage in the intake air heater circuit B. This indicates either a short to voltage in the wiring or a failed heater element, commonly found in diesel engines to improve cold-start performance.
The most common cause of P2608 (Intake Air Heater "B" Circuit High) is: Shorted intake air heater element
Typical repair costs for P2608 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains safe to drive. May experience harder cold starts in freezing temperatures, particularly with diesel engines.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2608 to identify the root cause.
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Quick Info
Category
Powertrain
System
Air Intake / Cold Start System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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