P0455 Jeep Code: Causes, Symptoms & Repairing EVAP Leaks

Have you suddenly seen the check engine light pop up in your Jeep? When you scanned it, did you get the P0455 trouble code? This fairly common OBD-II code often triggers that dreaded check engine light in Jeeps and other vehicles.

Seeing any error code when the check engine light comes on can be annoying and a bit worrying. What could be wrong with your vehicle? How serious is it? What will it take to fix? These are typical questions that go through your mind.

When P0455 shows up specifically, it indicates there’s an issue detected with the evaporative emission control system. Most likely there is a leak or open area somewhere that is allowing fuel vapors to escape when they should not.

Read on to learn what causes the P0455 code to show in your Jeep. We’ll discuss the evaporative emission system basics, look at symptoms related to the error, and how to diagnose and go about fixing P0455. With some focused inspection and targeted repairs, you’ll hopefully be able to resolve that P0455 Jeep trouble code quickly and get back on the road worry-free!

What Does the P0455 Code Mean Exactly in a Jeep?

Diagnostic trouble code P0455 is one of the more common check engine light codes Jeep owners can encounter. It is also referred to as:

• Evaporative emission system leak detected
• Evaporative emission control system leak detected
• Large leak detected in evaporative emission control system

This code being set indicates that the powertrain control module (PCM) has detected a large leak somewhere in the Jeep’s evaporative emission control system (EVAP).

Now what exactly is the evaporative emission control or EVAP system and what does it do? This is an emissions system that deals with fuel vapors that come from the fuel tank and fuel system components.

The EVAP system is designed to capture these fumes or vapors and store them, not allowing them to escape out into the atmosphere. The fuel vapors are contained until optimal times when they can be purged and burned within the engine.

So when the P0455 code sets, it means the EVAP system has sensed a significant leak happening somewhere within the system. This prevents the system from being able to properly contain and deal with evaporative fuel emissions as intended.

Jeep’s evaporative system is sealed and should maintain specific pressure for leak detection monitoring. A large 0.040 leak will trip the P0455 versus a small 0.020 leak more likely to trigger a P0456 code. But both indicate an issue losing vapor through leaks in the EVAP system.

What Causes the P0455 Code to Show Up in a Jeep?

There are a number of potential causes that can lead to the P0455 error code being set in your Jeep:

• Damaged, loose or missing gas cap
• Small hole or crack in the fuel tank
• Leaking, disconnected, or cracked EVAP hoses/lines
• Blocked or restricted hose or component
• Leak in the charcoal canister or mount
• Faulty canister purge valve
• Leaking fuel tank pressure sensor seal
• Small leak or holes anywhere in system
• Loose clamps or damaged fittings/seals

The P0455 code indicates one or more fairly large EVAP system leaks – potentially .040 inches or 1mm size. This means there are significant issues allowing fuel vapor loss from the system.

Smaller leaks may initially set a P0456 code before eventually tripping P0455 as the leak worsens. But the root cause is the same – some type of leak condition permitting vapor escape when driving.

Here are some of the more common places to check for leaks with this code:

Fuel Tank Cap Issues

One of the simplest causes turns out to be a loose, missing, or damaged fuel cap. The cap needs to seal correctly to maintain system pressure. If the cap is loose, faulty, or not tightened properly after fueling up, it can allow vapor loss that triggers P0455.

Leaking Fuel Tank

Cracks or holes anywhere in the fuel tank can allow fuel vapors to leak out. Small leaks may occur in seams or areas exposed to road debris damage. Larger leaks can happen from more significant cracking if the tank suffers corrosion or rust damage. Fuel may even drip or puddle under the tank if the leak source is on the bottom side.

Hose, Line, Fitting Leaks

The various rubber hoses, vapor lines, and connection fittings in the EVAP system are also common places for leaks. Typical issues include cracked,missing, disconnected, or improperly fitted hoses and components. Damage from wear, tight routing, or poor maintenance can lead to leaks.

Canister, Valves, Sensors

Major EVAP components mounted under the Jeep like the canister, purge valve, vent valves, sensors, and more have seals and connections that can leak. Any compromised or degraded seals, fittings, or component cracks allow fuel vapors to escape during operation.

Any Small Leak Source

Even very small holes or cracks anywhere in the evaporative emission plumbing can allow vapor loss large enough to set the P0455 error. The system is designed to be very tight and secure.

So there are lots of potential sources depending on your specific Jeep, its age/mileage, and maintenance history. Thorough inspection and leak tests are often needed to pinpoint the exact source of the leak(s) when this code is set.

What are the Symptoms Associated with P0455 in a Jeep?

When there is a large EVAP system leak causing P0455 to set, you may notice some possible symptoms:

Check Engine Light Illuminates

The most obvious sign is the check engine light or service engine soon light coming on. The PCM has detected the issue through EVAP system monitoring and sets the P0455 code which turns on the warning light.

Fuel Odor Inside Vehicle

You may smell fuel vapors inside the passenger cabin if the leak is significant enough to allow fumes to escape. This typically only occurs with a larger vapor leak versus smaller ones.

Engine Hard to Start or Stalling

An EVAP leak can potentially lead to engine starting or stalling issues. This is because the fuel system is not maintaining normal pressure and vapor handling when leaks are present.

Rough Idle

The engine may also idle roughly with the leak condition, particularly if a hose or component that impacts engine operation when idle is where the leak source is.

Reduced Power and Performance

You may notice somewhat reduced power and acceleration in some cases since the fuel system is not operating fully optimally. Although with smaller leaks this symptom may not be noticeable in terms of vehicle drivability.

Keep in mind also that you may not experience any discernible symptoms right away with a P0455 code. Depending on the leak source location and size, the light may come on before you notice anything wrong during normal driving.

How to Diagnose and Fix P0455 in a Jeep?

When this evaporative emissions DTC sets on your Jeep, the key steps are to properly diagnose the leak source and then repair the problem to stop vapor loss.

Here are tips on locating leaks and fixing P0455 in your Jeep:

Initial Testing – Read Codes and Data

• Use an OBD2 scanner to read engine fault codes – note any other codes set along with P0455
• Check freeze frame data for clues on when leak may have started
• Monitor EVAP system readiness status
• Clear codes and retest after driving to see if P0455 returns quickly

Do a Thorough Visual Inspection

• Check the gas cap first – remove and inspect for damage/missing gasket, make sure it seals tightly
• Look under Jeep for any fuel leaks dripping from tank, lines, or components
• Inspect fuel tank seams and below for cracks or holes
• Look along frame rails or shield areas for damaged/leaking lines
• Examine all EVAP hoses, valves, seals for disconnects, cracks, loose fittings
• Note condition of mounting brackets, damaged clamps, missing hardware
• Check fuel filler neck seal/gasket for any signs of leakage

Perform Diagnostic Leak Tests

• Use a smoke machine to pressurize system and pinpoint leak sources
• Try an EVAP system pressure test with a scan tool to identify leaks
• Monitor system operation with scanner to check for flow issues

Make Necessary Repairs to Fix Leaks

• Replace any aged, cracked, or damaged hoses/lines
• Tighten loose clamps or fittings
• Install new gaskets/seals at leak sources
• Replace faulty or leaking fuel tank, EVAP valves
• Clear any blocked vapor lines or hoses
• Correct loose, broken, missing fuel tank filler neck seals
• Clear out blocked or leaking charcoal canister
• Fix faulty electrical connections at sensors or valves

Properly diagnosing and repairing the source(s) of the EVAP leak will allow you to finally clear that pesky P0455 check engine light code for good. Let’s look at a few of the more details involved with these diagnostic and repair steps.

Pinpointing the Leak Source

Sometimes just a thorough visual inspection along with small handheld EVAP leak detectors can help you spot an obvious leak source like a disconnected EVAP hose.

But often, specialized leak detection testing is needed to pinpoint the exact location of elusive EVAP system vapor leaks:

Smoke Testing

EVAP smoke testing involves pressurizing the system with artificial vapor or smoke. As you watch the various components, leaks will become apparent when you see smoke escaping at the source. This can pinpoint even very minor leak points.

Pressure Testing

Using a scan tool, you can pressurize and monitor the EVAP system. A significant pressure drop indicates one or more system leaks. This helps narrow down the general location of the leak issue to then further inspect and test.

Using a combination of visual checks, EVAP system operation data, and testing techniques will allow you to zero in on the leak source(s) causing the P0458 trouble code.

Repairing the Leak Source

Once you’ve identified where the leak originates, you can go about properly repairing or replacing the specific component(s) involved. Some typical repairs include:

• Installing a new gas cap if damaged one allows vapor loss
• Tightening or replacing leaking hoses, seals, gaskets
• Replacing faulty purge valves or vent valves
• Repairing or replacing fuel tank, filler neck, or lines if cracked/leaking
• Clearing out contaminated charcoal canister if it has restricted flow
• Fixing electrical faults triggering erroneous leak codes

Properly sealing up identified large EVAP system leaks is the only real fix for P0455 in the long run.

What’s the Estimated Cost to Fix P0455 in a Jeep?

The cost to diagnose and repair P0455 in your Jeep can vary quite a bit. It depends on what’s ultimately causing the leak, how extensive it is, and what repairs are needed. Here are some typical repair cost estimates:

• Tightening/replacing gas cap – $20-$50
• Replacing damaged vapor lines – $100-$300
• Fixing leaking or cracked fuel tank – $300-$1000
• Replacing faulty EVAP valves – $200-$500
• Repairing multiple leaks – $500-$1500

Keep in mind you also have diagnostic fees to find leaks typically around $100. And costs go up if extensive removal of components is needed to access and fix the source.

But often, EVAP leaks can be resolved fairly easily and cost effectively, especially if caught early before major damage occurs. Even bigger jobs like fuel tank replacement may be necessary though after leaks have been occurring for awhile undetected.

Is it Safe to Drive with a P0455 Code?

The Jeep is generally safe to drive for a period of time with the P0455 trouble code present. The EVAP leak is unlikely to cause immediate drivability problems or safety issues in most cases.

However, it’s still important not to neglect the code. The P0455 should be properly diagnosed and repaired soon rather than continuing to drive it for months or longer with the leak present.

Driving long term with an unresolved large evaporative emission leak can lead to:

• Increased fuel odor in vehicle over time
• Check engine light constantly staying on
• EVAP monitor not able to run/pass testing cycles
• Potential stalling or performance problems

Additionally, ignoring P0455 long-term may lead to added repairs later if the leak is allowed to worsen and affect other components. So while not an immediate threat, it’s best to try to diagnose and fix P0455 leaks soon to avoid escalating evap issues down the road.

How Can I Try to Prevent P0455 Codes in My Jeep?

While not always possible to prevent leaks and codes entirely, keeping your Jeep EVAP system in top shape can reduce odds of issues:

• Use high-quality gas cap, ensure it seals tightly
• Replace cap once it reaches 5-7 years old
• Visually inspect system during tune ups or repairs
• Check under Jeep carefully for damaged/dangling lines
• Have any detected small leaks fixed promptly
• Keep fuel tank area clean, avoid debris causing leaks
• Ensure gas cap is tightened after refueling
• Follow Jeep maintenance schedule for EVAP component checks
• Fix minor damage before it worsens

Paying close attention to your Jeep’s evaporative emission system will help you spot potential problems early and avoid P0455 codes and leaks as much as possible. But some amount of EVAP trouble codes and repairs are practically inevitable as vehicles age.

Frequently Asked Questions About Jeep P0455 Codes

Does P0455 Cause Engine Damage in a Jeep?

The P0455 code itself does not cause any engine damage. However, driving for long periods with a real unresolved EVAP system leak allowing vapor escape can lead to engine issues over time.

Will a Loose Gas Cap Trigger P0455 in a Jeep?

Yes, very often a loose, damaged, or incorrectly installed gas cap causes the P0455 code. The cap is unable to maintain proper sealing and pressure. Replacing the faulty cap will commonly fix this type of leak.

Can I Reset P0455 Without Fixing the Leak?

You can use a scan tool to clear P0455, turning off the check engine light temporarily. But until the actual EVAP leak is found and repaired, the code will just keep returning. The light reset doesn’t fix the root issue.

Does a Small Leak Cause P0455?

No, only a fairly large 0.040 leak triggers the P0455. Smaller leaks under 0.020 inch size will set a P0456. But both indicate evap leaks needing repair.

Is it Safe Driving with P0455?

The Jeep will usually drive fine for awhile with a P0455 code. But it’s recommended you diagnose and repair it within weeks, not months, to avoid potential issues from emissions system damage over time.

Can I Reset P0455 Myself?

Yes, you can use an OBD2 scanner/reset tool to erase the P0455 trouble code. This turns off the check engine light. Professional diagnosis is still needed to fix the underlying leak causing the code though.

The Bottom Line on Jeep P0455 Codes

The P0455 code can be common in aging Jeeps as evaporative emission systems develop leaks. But finding and repairing the leak source is key to restoring proper operation.

Focus your diagnosis on common leak points like a bad gas cap, fuel tank issues, damaged hoses, faulty valves, and loose connections. Leak testing and thorough inspection will help zero in on the exact failure.

Repairing identified large evap system leaks then allows the P0455 code to be cleared for good. While sometimes requiring substantial work depending on the leak source, properly fixing P0455 will prevent driveability problems and restore your Jeep’s emission control system back to working order.