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P1506 Fault Diagnosis for 1999 Ford Escort 2.0L SPI - Idle Control Issues

Model: Ford Escort Fault Code: P1506 Posted: 2010-04-15 08:00

I've been experiencing a P1506 diagnostic code on my 1999 Ford Escort with a 2.0L SPI engine. I've already cleaned the throttle body and the carbon buildup near the EGR valve connection. The vehicle runs smoothly, maintaining steady RPMs between 900-1000, with no stalling or shaking. However, the EVAP system is currently not ready, which may be related. I came across a suggestion that plugging two holes in the throttle body might trick the engine control module (PCM) into thinking idle is under control — but I'm concerned this could cause long-term damage and is likely ineffective. What are the most common causes of P1506? And what steps should I take to properly diagnose and resolve this issue without risking further damage?

Related fault codes
P1506
Comments (3)
Anonymous 2010-04-15 13:46

The post lacks specific details like model year and engine type. Please provide those for more accurate troubleshooting. Possible causes of P1506 include: - Idle Air Control (IAC) valve shorted to ground - Damaged or malfunctioning IAC valve - Stuck IAC valve - Vacuum leaks in the intake system - Failed EVAP system (you mentioned it's not ready) - Faulty Powertrain Control Module (PCM)

Anonymous 2010-04-16 07:45

This is a 1999 Ford Escort with a 2.0L SPI engine. The car runs well — no hesitation, stalls, or rough idle. EVAP system status is currently 'not ready'.

Anonymous 2010-04-17 07:19

P1506 indicates the PCM detects an abnormally high idle speed and struggles to maintain stable idling. Since your vehicle runs smoothly under normal conditions, this code may be a residual issue from prior maintenance. Recommendation: Clear the P1506 code using an OBD2 scanner and monitor whether it returns. If it reappears, investigate potential issues such as a faulty Idle Air Control (IAC) solenoid or problems with the PCV valve and associated hoses. It's important to note that plugging holes in the throttle body is not recommended — this can lead to poor engine performance, increased emissions, and may cause damage over time.