# Intermittent No-Start, Cranks Fine 2020 Toyota Avalon

> ClearTheCode — Experiencing an intermittent no-start where your 2020 Toyota Avalon cranks but won't start? Discover common causes and practical diagnostic steps to resolve this frustrating issue.

Source: https://clearthecode.com/articles/intermittent-no-start-cranks-fine-toyota-avalon-2020
Author: ClearTheCode

# Intermittent no-start, cranks fine 2020 Toyota Avalon

Imagine getting into your 2020 Toyota Avalon, turning the key or pressing the start button, and hearing the engine crank normally – a healthy "whirr, whirr, whirr" – but it just won't catch and start. Then, later, it might start perfectly fine as if nothing ever happened. This frustrating and unpredictable issue, an intermittent no-start where the engine cranks but doesn't fire up, is a common concern for many vehicle owners, including those with a 2020 Toyota Avalon. It leaves you wondering if you'll be stranded next time you try to leave.

## What drivers notice on this 2020 Toyota Avalon

Drivers of the 2020 Toyota Avalon experiencing this issue often report a feeling of uncertainty and unreliability. The primary characteristic is the engine's ability to crank vigorously, indicating a healthy starter and battery, but a complete failure to ignite and run. This problem is not constant; it appears randomly, sometimes after the vehicle has sat for a while, or even after a short stop, only to disappear on the next attempt or after several tries. There's usually no accompanying check engine light during the no-start event, making diagnosis particularly challenging without proper tools and knowledge.

## At a glance: difficulty, repair cost, and diagnostic workflow

- **Difficulty Rating:** 6/10 — Easy to moderate
- **Common Symptoms:** Engine cranks strongly and at a normal speed but does not start or "catch."; The problem occurs randomly and inconsistently, making it difficult to reproduce on demand.; Vehicle may start after multiple attempts, after sitting for a while, or after wiggling the key.; No specific warning lights might illuminate on the dashboard during the no-start event.
- **Estimated Repair Cost:** $80–$900 (parts + typical shop labor)
- **OEM Tooling Required:** Standard OBD-II scanner and hand tools

**Diagnostic workflow:**
1. Confirm the symptom on your vehicle.
2. Scan for stored or pending codes with an OBD-II tool.
3. Inspect the most common causes in this guide (visual checks first).
4. Run verification tests before replacing parts.
5. Repair, clear codes, and verify on a test drive.

## Symptoms and warning signs

When your 2020 Toyota Avalon experiences an intermittent no-start, cranks fine condition, you might observe several key symptoms:
- Engine cranks strongly and at a normal speed but does not start or "catch."
- The problem occurs randomly and inconsistently, making it difficult to reproduce on demand.
- Vehicle may start after multiple attempts, after sitting for a while, or after wiggling the key.
- No specific warning lights might illuminate on the dashboard during the no-start event.
- You might notice the fuel pump hum is absent or inconsistent when the ignition is turned to the ON position.
- If checked, spark plugs may appear dry (indicating a fuel delivery issue) or potentially wet (indicating a lack of spark).
- The engine may briefly sputter or try to fire before dying, or it might not fire at all.

## How to verify and confirm the issue

Confirming an intermittent no-start on your 2020 Toyota Avalon requires careful observation and systematic checks during a no-start event:
- **Listen for the fuel pump:** When you turn the ignition to the ON position (without cranking), listen for a brief, faint hum from the rear of the vehicle. This indicates the fuel pump priming. If you don't hear it consistently during a no-start event, it's a strong indicator of a fuel delivery problem.
- **Check for spark:** If safe to do so and you have the right tools, use an inline spark tester to confirm if ignition is present at one of the coil packs during a no-start condition. No spark means an ignition system or sensor issue.
- **Scan for codes:** Even without a check engine light, use an OBD-II scanner to check for pending or stored diagnostic trouble codes (DTCs). Codes related to the crankshaft position sensor, camshaft position sensor, fuel pressure sensor, or immobilizer system can provide valuable clues.
- **Monitor live data:** A professional scan tool can monitor live data during a no-start event, looking at parameters like engine RPM during cranking, fuel pressure, injector pulse width, and spark advance. If the ECU doesn't detect RPM during cranking, it won't trigger spark or fuel injection.
- **Fuel pressure test:** A mechanical fuel pressure gauge can be connected to the fuel rail (if accessible) to confirm adequate fuel pressure during cranking. Compare readings to OEM specifications.
- **Observe security light:** Pay attention to the security light on the dashboard. If it flashes rapidly during cranking, it could indicate an immobilizer system issue preventing the engine from starting.

## Common causes (most likely first)

An intermittent no-start, cranks fine condition on your 2020 Toyota Avalon can stem from several potential issues:
- **Faulty Fuel Pump or Relay:** This is a very common culprit. If the fuel pump isn't consistently delivering fuel to the engine, or its relay is intermittently failing, the engine will crank but not start. Modern Toyota fuel pumps have experienced reliability concerns.
- **Crankshaft Position Sensor (CKP):** This sensor provides crucial engine speed and position information to the engine control unit (ECU). If it's failing intermittently, the ECU won't know when to fire the spark plugs or inject fuel, leading to a no-start.
- **Camshaft Position Sensor (CMP):** Similar to the CKP, the CMP sensor helps the ECU synchronize fuel injection and ignition. An intermittent fault can cause starting issues, especially if the signal is lost sporadically.
- **Ignition System Issues:** Worn spark plugs, failing ignition coils, or wiring problems can lead to an intermittent lack of spark, preventing combustion.
- **Immobilizer System:** A glitch in the vehicle's anti-theft system can prevent the engine from starting, even if it cranks. This could be due to a faulty key, transponder, or the immobilizer module itself.
- **Engine Control Unit (ECU) or Wiring:** Less common, but an intermittent fault within the ECU or its wiring harness connections can cause starting problems by failing to send critical commands.
- **Clogged Fuel Filter:** While less common on newer vehicles with long-life filters, a severely restricted fuel filter can intermittently starve the engine of fuel, especially under certain conditions.
- **Weak Battery or Charging System:** Although the engine cranks, a weak battery might not provide enough voltage for critical electronics (like the ECU or fuel pump) to operate correctly, especially if the problem is intermittent or temperature-sensitive.

### Related guides on this vehicle

- [1997 Toyota Avalon Won't Start After Sitting for Days](/articles/car-wont-start-after-sitting-3900-toyota-avalon-1997)
- [2020 Toyota Corolla: Car Won't Start, No Fuel Pump Prime Sound](/articles/car-wont-start-no-fuel-pump-prime-toyota-corolla-2020)
- [2020 Toyota Highlander: Car Won't Start, No Crank, No Power At All](/articles/car-wont-start-no-crank-no-power-8772-toyota-highlander-2020)

## Step-by-step diagnosis and fixes

Diagnosing an intermittent no-start on your 2020 Toyota Avalon requires a systematic approach:
1.  **Check for Fuel Pump Operation:**
    - Turn the ignition to ON (not start) and listen for the fuel pump hum. If absent, check the fuel pump fuse and relay. Swap the fuel pump relay with a known good, identical relay (e.g., horn relay) to test.
    - If still no hum and fuse/relay are good, consider a fuel pressure test or direct power test to the pump (professional recommended).
2.  **Verify Spark:**
    - Using a spark tester, check for spark at one of the ignition coils during a no-start event. If no spark, investigate ignition coils, spark plugs, and the crankshaft/camshaft position sensors.
3.  **Scan for DTCs:**
    - Connect an OBD-II scanner and check for any stored, pending, or historical codes. Pay close attention to codes related to engine sensors, fuel system, or immobilizer.
    - Monitor live data for engine RPM during cranking. If it shows 0 RPM, suspect the crankshaft position sensor.
4.  **Inspect Sensors and Wiring:**
    - Visually inspect the crankshaft position sensor, camshaft position sensor, and their wiring harnesses for damage, corrosion, or loose connections. Test sensor resistance or signal output if possible (requires a multimeter or oscilloscope).
5.  **Check Immobilizer System:**
    - Observe the security light on the dashboard. If it's flashing rapidly during cranking, consult your owner's manual or a locksmith/dealer for immobilizer diagnostics. Try a different key if you have one.
6.  **Fuel Pressure Test:**
    - If fuel pump operation is suspect, perform a fuel pressure test at the fuel rail during a no-start condition. Compare readings to OEM specifications. For more detailed troubleshooting, you can find many specific guides by visiting our All repair guides section.

## Repair options and cost factors

The cost and complexity of repairing an intermittent no-start on your 2020 Toyota Avalon will vary significantly depending on the root cause:
- **Fuel Pump/Relay:** A faulty fuel pump relay is inexpensive (often under $50 for the part). A fuel pump replacement can be more substantial, ranging from a few hundred to over a thousand dollars for parts and labor, as it often requires dropping the fuel tank or accessing it from under the rear seat.
- **Crankshaft/Camshaft Position Sensor:** These sensors are typically moderately priced (around $50-$200 for the part) and labor can vary depending on accessibility, often a few hours.
- **Ignition Components:** Spark plugs are relatively inexpensive, but ignition coils can add up, especially if multiple need replacement. Expect $50-$150 per coil.
- **Immobilizer System:** Repairing immobilizer issues can range from simple key reprogramming to replacing modules, which can be costly and often requires dealer-specific tools and programming.
- **Wiring/ECU:** Diagnosing and repairing wiring issues can be labor-intensive. ECU replacement is rare but very expensive, often requiring programming to the vehicle. Always consider using OEM or high-quality aftermarket parts for critical components to ensure reliability. For a broader look at various vehicle issues and solutions, feel free to browse our [Browse vehicles](/vehicles) section.

## When to see a professional

While some basic diagnostic steps can be performed by a DIY enthusiast, an intermittent no-start can be particularly challenging to diagnose due to its unpredictable nature. You should see a professional technician if:
- You lack the specialized tools (e.g., fuel pressure gauge, advanced scan tool, oscilloscope) required for thorough diagnosis.
- You've performed basic checks (fuel pump hum, fuse/relay) and haven't identified the problem.
- The issue is persistent and leaves you stranded, or you rely on your vehicle daily.
- You're uncomfortable working with vehicle electrical or fuel systems, which can be complex and potentially dangerous.
- The problem is potentially related to the immobilizer system, which often requires dealer-level programming and specialized equipment.
Professionals have the experience and equipment to accurately pinpoint intermittent faults and perform necessary repairs safely and efficiently.

## Frequently asked questions

### Why does my 2020 Toyota Avalon crank but not start sometimes?
An intermittent crank-no-start condition on your 2020 Toyota Avalon most commonly points to issues with the fuel delivery system (like a failing fuel pump or relay) or critical engine sensors such as the crankshaft or camshaft position sensors. These components are vital for the engine's computer to properly time fuel injection and spark, and an intermittent fault can prevent the engine from firing up reliably.

### Can a weak car battery cause an intermittent no-start even if it cranks?
Yes, a weak or failing battery can sometimes cause an intermittent no-start, even if the engine seems to crank normally. While the starter motor might still engage, a low battery voltage might not be sufficient to power other critical electronic components, such as the fuel pump, ignition coils, or the engine control unit (ECU), preventing the engine from firing up reliably.

### How can I prevent an intermittent no-start issue in my Toyota Avalon?
Preventing an intermittent no-start in your 2020 Toyota Avalon largely involves following the manufacturer's recommended maintenance schedule. This includes regularly checking your battery's health, replacing spark plugs at specified intervals, and addressing any dashboard warning lights promptly. While some component failures are unpredictable, proactive maintenance can help identify potential issues before they become critical.

## Sources and further reading

- Toyota Avalon Owner's Manual
- OEM Technical Service Bulletins (TSBs) for 2020 Toyota Avalon
- Automotive repair databases and service manuals

Disclaimer: This article provides general information and is not a substitute for OEM service procedures; always use a qualified technician for safety-critical work.

## Related pages
- All repair guides
- [Browse vehicles](/vehicles)

## Explore related guides on ClearTheCode

- [Browse OBD-II codes](/codes)
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