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Trouble code
P2609: intake air heater circuit
The same code points to different failures on different engines. Below, engine by engine, are the documented failures whose records name P2609, with the record's own words, how to tell them apart and the usual fix. The meaning above is taken from the record Grid heater bolt and relay failures (2019+ 6.7).
6.7 Cummins 2007-20186.7 Cummins 2019+
6.7 Cummins 2007-2018
1 documented failure names this code. All about this engine
verified
How widespread: Common
17 NHTSA owner complaints match it, out of 1,355 checked
Where its record names the code
- P2609 (intake air heater circuit) or a check-engine light can come first: owners report the code when the hardware has started to burn or break
- treat a P2609 / intake heater code as a reason to inspect the grid heater hardware before driving further
Its other signs
- sudden loss of power, knocking or clicking, then catastrophic engine damage once a broken nut or bolt reaches a cylinder (owners most often name cylinder #6)
- hard cold starts / no grid-heater cycling when the heater itself has failed separately
- the grid-heater terminal nut or bolt visibly burned, loose or broken on inspection (found before it lets go)
How to tell it apart
- treat a P2609 / intake heater code as a reason to inspect the grid heater hardware before driving further
- remove the intake horn and inspect the grid heater terminal nut and bolt for burning, looseness or breakage (shop check at any service visit)
- after a failure: borescope the cylinders (owners most often report #6) and inspect the intake manifold for missing hardware before restarting
Usual fix
prophylactic: replace the factory grid heater with a retention/upgrade kit or an intake design without the internal fastener - cheap insurance against engine damage
Recalls and bulletins
TSB 9003585TSB 18-005-13
Root cause, parts and sources →
6.7 Cummins 2019+
1 documented failure names this code. All about this engine
verified
How widespread: Common
22 NHTSA owner complaints match it, out of 318 checked
Where its record names the code
- code P2609 (intake air heater circuit) and P0542; long crank and white smoke in cold weather
- take P2609 seriously: inspect the heater grid terminal hardware before replacing the relay alone
Its other signs
- knocking at speed after the heater's terminal nut or bolt breaks off and is pulled into a cylinder (owners most often name cylinder 6)
- smoke or fire from the heater grid relay on 2021-2023 trucks (recalled)
How to tell it apart
- take P2609 seriously: inspect the heater grid terminal hardware before replacing the relay alone
- check the VIN for the relay recalls on 2021-2023 trucks
- verify relay operation and voltage drop at the studs at key-on
Usual fix
repair the relay/circuit; reseal or replace the grid heater assembly (retention bolts with the update kit)
Recalls and bulletins
23V-06021V-79821V-163
Root cause, parts and sources →
A code tells you which system flagged a fault, not which part failed. Read it with the signs your truck shows: symptoms by engine. For your exact truck: check your VIN.