Throttle Control Relay Circuit Intermittent
The P2549 code means the vehicle's onboard diagnostic system has detected: Throttle Control Relay Circuit Intermittent. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $80 - $400 (parts and labor)
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Common Symptoms
- Intermittent reduced power mode
- Sporadic throttle response loss
- Check engine light comes and goes
- Occasional idle-only operation
Probable Causes (Ranked by Likelihood)
- Loose throttle relay connector or socket Very High
- Worn relay contacts causing intermittent connection High
- Chafed wiring in relay control circuit Moderate
- ECM ground issue affecting relay driver Low
Step-by-Step Diagnostic Procedure
-
Wiggle test relay while monitoring throttle response
-
Inspect relay socket for loose or spread terminals
-
Check relay control wiring for abrasion damage
-
Test ECM grounds for proper continuity and torque
Frequently Asked Questions
Why does reduced power mode come and go?
The intermittent relay connection means the throttle body loses power briefly, triggering fail-safe mode. When the connection restores, normal operation resumes until the next dropout.
Can vibration cause P2549?
Yes. Road and engine vibration can cause a marginally loose relay to lose contact momentarily, triggering the intermittent fault.
Should I replace the relay or the socket?
Start with the relay as it is cheaper and easier. If the problem persists, the relay socket may need new terminals or replacement.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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