P0338 medium Severity

P0338: Crankshaft Position Sensor A Circuit High Input

May cause difficulty starting, misfires, rough idle, loss of power, stalling or a no‑start condition due to incorrect crankshaft position data.

Overview

OBD‑II P0338 indicates that the engine control module has detected a voltage signal higher than expected from the crankshaft position sensor A circuit, often due to sensor fault, wiring issues, or module faults.

Common Symptoms

  • Check engine light illuminated
  • Difficulty starting or no start
  • Engine misfires or runs rough
  • Loss of power or hesitation during acceleration
  • Poor fuel economy

Most Common Causes

Faulty crankshaft position sensor high

Sensor internal failure can send incorrect voltage causing high input detection.

Damaged or shorted wiring/connectors in the CKP circuit high

Corroded, frayed, or grounded wiring can lead to abnormal voltage signals.

Poor sensor ground connection medium

Inadequate ground may lead to elevated signal readings at the PCM.

Faulty engine control module (PCM/ECM) low

Rare; control module input circuitry malfunction may misinterpret normal signals.

Over‑voltage on reference supply (charging system anomaly) low

Alternator/regulator issues may raise reference voltage leading to high sensor readings.

Diagnostic Steps

  1. Connect an OBD‑II scanner and confirm P0338 and any additional codes.
    Expected: P0338 stored without conflicting codes.
    Interpretation: Confirms relevant trouble code before further diagnosis.
  2. Visually inspect CKP sensor, wiring harness, and connectors for damage or corrosion.
    Expected: No visible breaks, corrosion, or oil/contaminant intrusion.
    Interpretation: Damage here can cause abnormal voltage signals.
  3. Measure reference voltage to CKP sensor with ignition on (engine off).
    Expected: Approximately 5 volts (vehicle‑specific).
    Interpretation: Deviation suggests wiring/ECM reference supply issues.
  4. Check sensor signal and resistance with multimeter per OEM spec.
    Expected: Signal within target range and resistance matches spec.
    Interpretation: Out‑of‑range indicates sensor fault.
  5. Use oscilloscope or live data to observe waveform while cranking.
    Expected: Stable waveform without spikes or noise.
    Interpretation: Spikes or erratic data point to wiring/sensor issues.
  6. If sensor/wiring tests good, test or swap known good PCM.
    Expected: Code clears and does not reappear.
    Interpretation: Indicates PCM input stage failure if prior steps were normal.

Repair Solutions

Replace crankshaft position sensor medium
Estimated Cost: $80 - $300

OEM sensor recommended; cost varies by vehicle.

Repair or replace damaged wiring/connectors medium
Estimated Cost: $50 - $200

Repair may require harness splice or connector replacement.

Clean and secure ground connections easy
Estimated Cost: $5 - $50

Ensure sensor and PCM grounds have low resistance contact.

Replace PCM/ECM (rare) hard
Estimated Cost: $600 - $1200

Only after exhaustive testing indicates control module fault.

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Replacing crankshaft sensor without checking wiring harness or connectors first.

Frequently Asked Questions

What does the P0338 code mean?

The P0338 code stands for Crankshaft Position Sensor A Circuit High Input. This generally indicates an issue with the Sensors system.

Is it safe to drive with a P0338 code?

The P0338 code is considered medium severity. May cause difficulty starting, misfires, rough idle, loss of power, stalling or a no‑start condition due to incorrect crankshaft position data.

How do I know if I have code P0338?

Common symptoms include: Check engine light illuminated, Difficulty starting or no start, Engine misfires or runs rough. You might also notice the Check Engine Light is on.

Common triggers for the P0338 error

This code is frequently triggered by: Faulty crankshaft position sensor, Damaged or shorted wiring/connectors in the CKP circuit, Poor sensor ground connection.

Estimated repair costs for different causes of P0338

It depends on what needs to be fixed. Clean and secure ground connections repairs are cheaper (~$50), while Replace PCM/ECM (rare) repairs are on the higher end (~$1200).

Does code P0338 apply to Dodge vehicles?

The P0338 code is a generic powertrain code, meaning it applies to almost all makes and models, such as Honda, Toyota, VW, Ford, and Chevy.

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