P0505 on 2014-2019 Jaguar F-TYPE: Idle Control Fault Causes and Fixes

What's Unique About the 2014-2019 Jaguar F-TYPE

Unlike many vehicles where P0505 points directly to a faulty Idle Air Control (IAC) valve, the Jaguar F-TYPE's supercharged AJ126 (V6) and AJ133 (V8) engines do not have a separate IAC valve and are highly susceptible to vacuum leaks. A manufacturer Technical Service Bulletin (SSM74375) confirms that P0505 is often triggered by air intake system leaks. Owners frequently find this code accompanied by lean codes (P2187, P2189), reinforcing that the root cause is unmetered air entering the engine from sources like a failed PCV valve or cracked hoses, rather than a primary failure of the throttle body itself.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Rough, fluctuating, or hunting idle
• Idle speed is too high or too low
• Engine stalling when coming to a stop or at idle
• Hissing or whistling sound from the engine bay, particularly from the rear of the engine near the firewall or from the passenger-side camshaft cover.
• Engine may be difficult to start
• In some cases, a 3000 RPM rev limit in Park or Neutral may be engaged as a protective measure.

Most Likely Causes

1. Failed PCV Valve Diaphragm 🔴 High Probability The rubber diaphragm inside the PCV valve assembly, located on the right-hand (passenger side in LHD cars) camshaft cover, is known to tear on Jaguar's 3.0L V6 and 5.0L V8 engines. This creates a significant vacuum leak. Jaguar issued TSB SSM74375 specifically addressing this failure mode.
   How to confirm: A loud hissing or sucking sound may be audible from the PCV valve. During a smoke test, smoke will emerge from the round PCV valve cap. A simple, though less definitive, test is to try and remove the oil filler cap while the engine is running; extreme suction making it very difficult to remove points to a large vacuum leak, likely the PCV diaphragm.
   Typical fix: Replace the PCV diaphragm and cap. 🎬 Watch this detailed DIY guide for replacing the PCV diaphragm. Jaguar now sells a diaphragm repair kit (Part No. C2D60163) as an alternative to replacing the entire camshaft cover. The V6 engine has two diaphragms, while the V8 has four. Aftermarket kits are widely available.
   Est. part cost: $20-$60 for diaphragm kits, $150+ for a full camshaft cover.
2. Cracked or Disconnected Vacuum Hoses 🔴 High Probability The complex plumbing around the supercharger and intake manifold includes numerous plastic and rubber hoses that become brittle with age and heat cycles. A common failure point is a small, soft hose at the back of the engine under the fuel rail.
   How to confirm: Perform a smoke test to see smoke escaping from a cracked hose. Common leak points are the ribbed 'symposer' hose behind the supercharger, the brake booster vacuum line, and other small lines connected to the intake manifold.
   Typical fix: Replace the specific cracked hose. In some cases, a generic vacuum hose of the correct diameter can be used as a substitute for a pre-formed OEM hose. Due to difficult access for some hoses at the rear of the engine, this can be a labor-intensive repair.
   Est. part cost: $15-$150 depending on the specific hose.
3. Dirty or Failing Electronic Throttle Body (ETB) ⚪ Low Probability While less common than vacuum leaks, carbon buildup around the throttle plate can restrict its movement, preventing it from closing properly and causing the PCM to lose idle control. The electronic components can also fail, but this is rare.
   How to confirm: After ruling out all possible vacuum leaks with a thorough smoke test, inspect the throttle body for heavy carbon deposits. Test the throttle body's electronic function with a high-end scan tool, observing commanded vs. actual throttle position.
   Typical fix: Clean the throttle body and throttle plate with a dedicated, throttle-body-safe cleaner. Do not scrub aggressively, as the throttle body has a special coating. If cleaning doesn't resolve the issue and the part is confirmed to be faulty, the entire Electronic Throttle Body must be replaced. An idle re-learn procedure may be required after cleaning or replacement.
   Est. part cost: $300-$700

Rare But Worth Checking

• Leaking Intake Manifold Gaskets: While not a primary suspect, these gaskets can fail and cause a vacuum leak. This would be clearly identified during a smoke test and is more common on higher-mileage vehicles.
• Leaking Vacuum Pump Seal: The engine's vacuum pump is a known source of oil leaks on these engines, but a failure of its seals could also potentially introduce an air leak.
• Leaking Supercharger Gasket/Seals: The gaskets between the supercharger and the intercoolers, or the main gasket between the supercharger and the engine block, can fail and create a significant vacuum leak.

Diagnosis Steps

1. Read the codes with an OBD-II scanner and confirm P0505 and any accompanying codes like P2187, P2189, or P0507. Note the freeze frame data.
2. Visually inspect the engine bay for any obviously disconnected, cracked, or broken vacuum hoses, paying close attention to the PCV system and hoses around the supercharger.
3. With the engine running, listen carefully for any hissing or whistling sounds that would indicate a vacuum leak. The PCV valve area on the passenger-side cam cover is a prime location to listen.
4. Perform a professional smoke test. This is the most critical step. Introduce smoke into the intake system (after the MAF sensor) and watch for where it escapes. Check the PCV valve caps, all vacuum lines (especially at the rear of the engine), intake manifold gaskets, and the throttle body shaft.
5. Based on the smoke test results, replace the faulty component (e.g., PCV diaphragm, cracked hose, or gasket).
6. If no vacuum leaks are found after a thorough smoke test, inspect the throttle body for heavy carbon buildup and clean it with an appropriate cleaner. Ensure the throttle plate moves smoothly.
7. After any repair, clear the trouble codes. Start the engine and let it idle for several minutes to allow the PCM to relearn idle trims. Perform a test drive to ensure the issue is resolved.

Parts You'll Likely Need

• PCV Valve Diaphragm Repair Kit (OEM #C2D60163) — This is the most frequent failure point causing vacuum leaks that trigger P0505 and associated lean codes on the F-TYPE's AJ126 and AJ133 engines.
  Trusted brands: Genuine Jaguar, URO Parts, RKX, EuroAMP
  OEM price range: $25-$40 (per kit)
  Aftermarket price range: $15-$30 (per kit)
• Vacuum Hose / Breather Hose — Plastic and rubber hoses in the engine bay become brittle and crack, creating vacuum leaks. The specific hose will depend on the location of the leak found during a smoke test. Hoses at the rear of the engine are common culprits.
  Trusted brands: Genuine Jaguar
  OEM price range: $50-$150
  Aftermarket price range: $15-$75
• Right Side Camshaft Cover (V6) (OEM #T2R93535 (supercedes AJ814002, C2Z29186)) — Before the diaphragm kit was available, the entire cover had to be replaced. This is now only necessary if the cover itself is cracked or damaged during a botched diaphragm replacement.
  Trusted brands: Genuine Jaguar
  OEM price range: $150-$250

Related Codes That Often Appear With This One

• P2187 — System Too Lean at Idle (Bank 1). This code is frequently paired with P0505 because the root cause, a vacuum leak, allows unmetered air into the engine, creating a lean condition that the PCM detects at idle.
• P2189 — System Too Lean at Idle (Bank 2). Similar to P2187, this indicates a lean condition on the opposite cylinder bank, caused by the same vacuum leak.
• P0507 — Idle Air Control System RPM Higher Than Expected. This code is a more specific version of P0505. The extra air from a vacuum leak causes the idle RPM to be higher than the target set by the PCM.

Technical Service Bulletins (TSBs) & Recalls

• SSM74375: States that an air intake system leak can cause P0505, P2187, P2189, or P0507 to be stored in the PCM. It identifies a split PCV diaphragm as the cause and provides part number C2D60163 for a lower-level repair kit.

Platform-Specific Known Issues

• A known issue, documented in Jaguar TSB #SSM74375, is that an air intake system leak from a split PCV diaphragm can cause DTC P0505 to be stored, often along with P2187, P2189, and P0507. The TSB advises using repair kit C2D60163 instead of replacing the whole cam cover.

Mechanic-Grade Diagnostic Values

• Short-Term Fuel Trims (STFT) at idle — expected: Close to 0%, typically within +/- 10%. Failure: Consistently high positive values (e.g., +25% or higher) on one or both banks strongly suggest a vacuum leak, as the PCM is adding fuel to compensate for unmetered air.
• Engine Ground Voltage Drop — expected: Well under 0.5V (500mV). Failure: A reading higher than 500mV while cranking the engine indicates a poor ground connection, which can cause erratic sensor readings and PCM behavior.

Scan Tool Commands That Help

• Jaguar SDD (Symptom Driven Diagnostics): Air Path Calibration / Air path set-up routine — This function should be run after cleaning or replacing the throttle body. It resets the open and closed positions of the throttle valve and other air control valves to ensure proper calibration and idle control.
• Manual Procedure (No Scanner): Throttle Pedal Reset — After disconnecting the battery or cleaning the throttle body, a manual relearn can be attempted. Turn the key to the 'ON' position (engine off), slowly press the accelerator pedal to the floor and release it completely. Repeat this twice, then start the car without touching the accelerator.
• Manual Procedure (Hard Reset): ECU Hard Reset and Idle Relearn — To clear all learned adaptations, disconnect the negative battery terminal for at least 15 minutes. After reconnecting, turn the ignition on (engine off) for 60 seconds, then turn off for 60 seconds. Start the engine without touching the gas pedal and let it idle for at least 10 minutes to allow the ECU to relearn idle trims with the clean throttle body.

Wiring & Ground Locations

• Main Engine/Transmission Ground Strap — A large braided stainless steel strap located on the passenger side (LHD) of the vehicle, connecting the transmission/engine block area to the chassis frame rail, often visible from underneath the car.. A poor engine ground can cause incorrect readings from sensors managed by the PCM, including the throttle position sensor, leading to idle control problems. A voltage drop test should be performed on this strap if electrical issues are suspected.
• Bulkhead Ground Points — On the firewall (bulkhead) in the engine bay, often near where the diagonal bracing rods attach or inboard of the starter relay.. These points provide ground for various engine bay components and sensors. Corrosion or looseness here can lead to intermittent and hard-to-diagnose electrical faults affecting engine management.
• Throttle Body Connector (C1E137C) — A 6-pin black connector located on the top front of the engine, LH side, directly on the electronic throttle body.. This is the primary electrical connection for the throttle body. Checking for corrosion, pin fitment, and correct voltage/signal on these pins is a key step if a throttle body electrical fault is suspected after ruling out vacuum leaks.

Real Owner Repair Stories

• YouTube user Alex Revive (Jaguar F-Type (year not specified)) — Check Engine Light with codes P2187 and P2189 (System Too Lean at Idle, Banks 1 & 2).
  ❌ Tried (didn't work) Replacing the PCV diaphragm, which is the most common fix, did not solve the problem.
  ✅ What actually fixed it After extensive smoke testing, the leak was found in a broken pipe for the 'symposer' system, which pipes engine noise into the cabin. Replacing the broken symposer pipe resolved the lean codes.
• JaguarForums.com user (2018 F-Type 400 Sport) — Check Engine Light with codes P2187 and P2189 after 6 starts / 75km of driving.
  ❌ Tried (didn't work) A dealer replaced the PCV diaphragm, but the codes returned.
  ✅ What actually fixed it The owner was still diagnosing, but the failure of the common PCV fix points towards a more elusive vacuum leak, such as a cracked hose or intake gasket, which is a common pattern for this vehicle.

"I Checked Everything" — The Actual Cause

• In some cases, a smoke test may not reveal a leak if the crack is small or only opens under specific temperature or vacuum conditions. A very subtle leak could also originate from the brake booster check valve or the booster diaphragm itself, which can be difficult to isolate with a smoke test. If a smoke test is clean, the next step is to investigate components that can fail intermittently or in ways a smoke test won't show, such as a faulty fuel rail pressure sensor causing false lean readings.