P2606

Code

Generic P — Powertrain

Intake Air Heater B Circuit Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 45 RU: 35

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Page language: EN

Causes

Open or shorted wiring in the intake air heater B circuit
Faulty intake air heater element (heater B)
Poor connector or terminal connection (corrosion, loose pin, water intrusion)
Failed relay or fuse supplying the heater circuit
Faulty PCM or control module output for heater B
Intermittent harness damage (pinch, chafe) or short to battery/ground

Symptoms

Check Engine Light (MIL) illuminated
Extended cold-start cranking or poor cold start performance
Possible rough idle until engine warms (depending on system)
Stored DTC(s) related to intake air heater/glow system
Intermittent fault behavior (code may be sporadic)

What to check

Scan for codes and view freeze frame / readiness status
Check for other related DTCs (glow plugs, heater A, PCM faults)
Inspect wiring harness and connectors for heater B (visible damage, corrosion, water)
Verify fuse and relay feeding the intake air heater circuit
Measure supply voltage at the heater connector with key on and while commanded
Measure resistance of the heater element B (with power removed)

Signal parameters

Supply voltage at heater connector should be near battery voltage when heater command is active (typically ~12 V)
Heater element resistance should be low (single-digit ohms depending on design) — compare to vehicle spec
Control signal often PWM or switched ground from PCM; expected duty cycle varies with engine/ambient conditions
Current draw should match manufacturer specification when heater B is energized (abnormal low or high current indicates open or short)
PCM should report heater B as commanded ON during warm-up or test conditions

Diagnostic algorithm

Read and record all stored and pending codes, freeze frame data and live data related to intake air heater operation.
Confirm the conditions required to set the code (ambient temperature, engine state, ignition key position). Recreate if safe and practical.
Visually inspect harnesses, connectors and heater elements for damage, corrosion, melted insulation, or water entry. Repair any obvious defects.
With ignition off, disconnect the intake air heater B connector. Measure resistance of the heater element to ground and between its terminals. Compare to spec. An open or very high reading indicates a failed heater.
With connector disconnected, check for battery voltage at the supply terminal with ignition on (not cranking) — verify fuse/relay continuity if no voltage.
Reconnect and back-probe the heater connector. Command the heater ON with a scanner while monitoring voltage and current. Expected: supply near battery voltage and current within spec. Abnormal low voltage or no current indicates open/relay/fuse; excessive current indicates shorted heater or wiring.
If voltage is present but heater resistance is correct and current is low, check for high-resistance connections (clean/repair terminals).
If wiring, fuse and relay check good but the PCM output does not command or shows incorrect duty/current, test the PCM output driver per factory procedure. Replace PCM only after confirming external components are good.
After repairs, clear codes, perform the required readiness/monitor tests and verify the code does not return under the same operating conditions.