Code result
P2029
Fuel Fired Heater Disabled
Moderate severity
What it means
The fuel-fired auxiliary heater (used to warm coolant or DEF on cold start) has been disabled by the control module — typically because of repeated start failures, low-voltage supply, or a self-protection condition.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Heater glow plug failed
highOne of the most commonly reported causes for this code — check this first.
Low battery voltage triggered lockout
mediumA plausible cause — test and verify before replacing parts.
Fuel supply starved — empty tank or pump weak
mediumA plausible cause — test and verify before replacing parts.
Related help
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