P0335 P0336 P0337 P0338 and P0339 Crankshaft Sensor Codes Explained

P0335, P0336, P0337, P0338, and P0339 are OBD2 trouble codes related to the crankshaft position sensor “A” circuit. They do not all indicate the same failure:

P0335 means the engine control module cannot recognize a valid crankshaft position signal.
P0336 means the signal is present but its pattern or timing is outside the expected range.
P0337 means the circuit input is lower than expected.
P0338 means the circuit input is higher than expected.
P0339 means the signal is intermittent.

A crankshaft sensor code does not automatically mean the sensor needs to be replaced. The correct repair may involve the connector, wiring, sensor power or ground, battery, starter, sensor clearance, reluctor wheel, or mechanical timing.

This guide focuses on what to check and how to match the test result to the correct repair.

P0335–P0339 Quick Diagnosis and Repair Chart

Code	What the ECM detected	Check first	Likely repair if confirmed
P0335	No valid CKP “A” signal	Cranking RPM, connector, power, ground, and signal	Repair the circuit, correct the air gap, or replace a failed sensor
P0336	CKP signal pattern is out of range	Cranking speed, sensor installation, reluctor wheel, and waveform	Correct sensor clearance, repair the reluctor, restore timing, or replace a weak sensor
P0337	CKP circuit input is too low	Short to ground, poor supply, excessive air gap, or weak VR output	Repair the short or high resistance, restore power/ground, or correct the air gap
P0338	CKP circuit input is too high	Short to voltage, open signal wire, or missing ground	Repair the open/short, restore sensor ground, or replace a sensor that cannot switch
P0339	CKP signal drops out intermittently	Connector tension, heat-damaged wiring, harness movement, and hot sensor operation	Repair terminals/wiring or replace a sensor that fails under heat or vibration

The exact thresholds and test conditions vary by vehicle. Use the wiring diagram and manufacturer specifications before applying voltage or resistance limits.

Before Replacing Anything: Perform These Three Checks

1. Save the Codes and Freeze-Frame Data

Do not clear the codes immediately.

Record all stored and pending codes, including camshaft sensor, system-voltage, misfire, and cam/crank correlation codes. Freeze-frame data may show whether the fault occurred during starting, idling, acceleration, or a hot restart.

The operating condition matters. A P0339 code that appears only after the engine heats up requires a different approach from a permanent P0335 code during every start attempt.

2. Check Engine RPM While Cranking

Open Engine RPM in the scan tool’s live data and crank the engine.

0 RPM while the starter turns the engine: the ECM may not be receiving a usable CKP signal.
A normal-looking cranking RPM: the ECM is receiving enough CKP information to calculate speed, but individual pulses may still be missing or incorrectly timed.
RPM appears and suddenly drops to zero: suspect an intermittent sensor, connector, wiring, or power/ground problem.

Zero RPM is especially useful when diagnosing a P0335 code, but it does not prove that the sensor itself is defective.

Before testing the sensor circuit, scan for trouble codes and check engine RPM while cranking. The MUCAR BT200 MAX can display supported live data and help you record the clues that guide the next test. A code or RPM reading alone does not confirm that the CKP sensor is faulty.

Phone-Based Diagnostics

MUCAR BT200 MAX

Check the Clues Before Replacing the Sensor

Read fault codes and view supported live data, including engine RPM while cranking, from your phone. Use those results to decide what to test next—not as proof that the CKP sensor has failed.

Explore BT200 MAX

3. Inspect the CKP Sensor Circuit

Inspect the crankshaft position sensor and its harness before testing or replacing parts.

Crankshaft position sensor connector wiring air gap and reluctor wheel inspection points for P0335 diagnosis

Look for:

Oil, coolant, or water inside the connector
Bent, corroded, spread, or pushed-back terminals
A connector that is not fully locked
Wiring melted against the engine or exhaust
Chafed wiring near the starter or transmission
Harness tension caused by engine movement
Loose sensor mounting hardware
A sensor that is not fully seated
Metal debris on a magnetic sensor
Visible reluctor-wheel damage

A loose terminal or damaged wire can cause every code in the P0335–P0339 family.

For complete two-wire, three-wire, multimeter, and oscilloscope procedures, see How to Test a Crankshaft Position Sensor.

P0335 Code: Crankshaft Position Sensor “A” Circuit

The P0335 code means the ECM cannot recognize a valid signal from the crankshaft position sensor “A” circuit.

A P0335 engine code may cause extended cranking, a crank-but-no-start condition, stalling, or an RPM reading that remains at zero while cranking.

What to Check for P0335

Start with the Engine RPM PID:

Crank the engine while monitoring RPM.
If RPM stays at zero, inspect the CKP connector and wiring.
Identify whether the sensor is a Hall-effect, variable-reluctance, or another active design.
Test the specified power and ground on an active sensor.
Test for CKP signal activity while cranking.
If the signal exists at the sensor, check whether it reaches the ECM.
If the electrical circuit passes, inspect sensor clearance and the reluctor wheel.

How to Fix P0335

Use the test result to choose the repair:

Test result	Repair
No sensor power	Repair the power-supply circuit, fuse, splice, shared reference circuit, or module connection
Poor sensor ground	Repair the ground wire, connector, splice, or related module ground
Signal at the sensor but not at the ECM	Repair the open, short, or high resistance in the signal wire
Correct power and ground but no sensor output	Confirm that the reluctor is moving and the air gap is correct; replace the sensor if those checks pass
Weak VR sensor output during cranking	Check the battery, starter speed, air gap, debris, and reluctor before replacing the sensor
Damaged or missing reluctor teeth	Repair or replace the reluctor, flywheel, flexplate, or related component
Sensor not fully seated	Clean the mounting surface, install the correct sensor, and tighten it to specification

Do not call sensor replacement the universal P0335 fix. A new P0335 crankshaft sensor will not repair a missing ground, broken wire, slow starter, or damaged trigger wheel.

P0336 Code: Crankshaft Position Sensor Range/Performance

The P0336 code means the ECM receives a crankshaft signal, but the signal’s timing, frequency, amplitude, or pulse pattern is not what it expects.

This distinction is important: P0335 often involves a missing usable signal, while P0336 usually involves a signal that is present but implausible.

What to Check for P0336

For code P0336, focus on signal quality and mechanical accuracy:

Check battery voltage and cranking speed.
Make sure the sensor is the correct part and is fully seated.
Check the specified sensor-to-reluctor air gap.
Inspect the sensor tip for metal debris.
Inspect the reluctor wheel for damaged, missing, or uneven teeth.
Check for a loose or shifted reluctor.
Graph engine RPM and synchronization data.
Use an oscilloscope if the basic checks do not identify the fault.
Compare CKP and CMP signals if mechanical timing is suspected.

If the basic checks do not explain the fault, inspect the CKP signal with an oscilloscope. The THINKSCAN 689BT supports compatible oscilloscope expansion, but waveform capture requires separate compatible hardware. The scanner alone cannot display a raw CKP waveform.

How to Fix P0336

Finding	Repair
Low cranking speed	Charge or replace the battery after testing; repair excessive cable voltage drop or a weak starter
Sensor installed incorrectly	Reinstall the correct sensor and verify its mounting and clearance
Metal debris on a magnetic sensor	Remove the sensor, clean the tip safely, and investigate the source of excessive debris
Excessive air gap	Correct the mounting, replace a damaged bracket, or install the correct sensor
Weak or distorted signal with a good target	Replace the confirmed weak sensor
Damaged reluctor teeth	Repair or replace the reluctor, flywheel, flexplate, or crankshaft-related target
Reluctor has shifted	Correct or replace the affected mechanical component
CKP/CMP relationship is shifted	Inspect the timing belt, timing chain, tensioner, cam phaser, and mechanical timing
Electrical noise in the waveform	Repair shielding, grounding, routing, or wiring damage near ignition and high-current circuits

A P0336 crankshaft position sensor code should not be diagnosed from resistance alone. A sensor may pass a static resistance test but generate an incorrect waveform during cranking or operation.

P0337 Code: Crankshaft Position Sensor Circuit Low Input

The P0337 code indicates that the CKP “A” circuit input is lower than expected.

On a Hall-effect circuit, the signal may be shorted to ground or unable to switch high. On a variable-reluctance sensor, the generated AC signal may be too weak for the ECM to recognize.

What to Check for P0337

Confirm battery voltage and cranking speed.
Check the signal wire for a short to ground.
Test sensor power and ground if the sensor is active.
Check for corrosion or high resistance in the connector.
Inspect the air gap and sensor installation.
Test VR sensor AC output while cranking when applicable.
Compare the reading at the sensor with the reading at the ECM.

How to Fix P0337

Repair a signal wire shorted to ground.
Repair corroded or high-resistance terminals.
Restore the specified sensor power supply.
Repair excessive resistance in the ground circuit.
Correct excessive sensor clearance.
Repair low cranking speed before judging VR sensor output.
Replace the sensor only when its supply, ground, wiring, air gap, and target are correct but its output remains below specification.

Do not use a universal minimum voltage for P0337. The correct value depends on the sensor design and vehicle.

P0338 Code: Crankshaft Position Sensor Circuit High Input

The P0338 code indicates that the CKP “A” circuit input is higher than expected.

A Hall-effect signal may remain near its pull-up voltage when the signal wire is open, the sensor ground is missing, or the sensor cannot switch the circuit low. Therefore, seeing approximately 5 volts does not prove that the sensor is working.

What to Check for P0338

Check the signal circuit for a short to voltage.
Verify the sensor ground under load.
Inspect the connector for backed-out or loose terminals.
Back-probe the signal and confirm that it switches while cranking.
Compare the signal at the sensor and ECM.
Confirm that the reluctor wheel is rotating and the sensor clearance is correct.

How to Fix P0338

Finding	Repair
Signal wire shorted to voltage	Locate and repair the damaged wire or connector
Open signal wire	Repair the open circuit between the sensor and ECM
Missing sensor ground	Repair the ground circuit or terminal
Voltage reaches the sensor but the output remains fixed	Confirm target movement and air gap; replace the sensor if both are correct
Sensor switches correctly but the ECM sees a fixed high signal	Repair the harness or ECM connector
Incorrect replacement sensor	Install the correct sensor for the exact engine and position

Do not replace the ECM because of P0338 until the wiring, terminals, power, ground, and signal have been tested at both ends of the circuit.

P0339 Code: Crankshaft Position Sensor Circuit Intermittent

The P0339 code means the ECM intermittently loses a valid CKP “A” signal.

A vehicle with code P0339 may start and run normally during testing. The fault may appear only when the sensor becomes hot, the engine moves under load, the vehicle hits a bump, or moisture enters the connector.

What to Check for P0339

Use the conditions recorded in the freeze-frame data to reproduce the fault.

Graph Engine RPM while starting and driving.
Check whether RPM drops suddenly when the engine stalls.
Perform a careful harness movement test.
Inspect terminal tension rather than checking only for visible corrosion.
Monitor sensor power, ground, and signal together.
Repeat the test after the engine reaches operating temperature.
Record the waveform if the failure occurs too quickly for a multimeter.
Inspect the reluctor for looseness or movement.

How to Fix P0339

Replace loose, spread, burnt, or corroded connector terminals.
Repair a partially broken conductor rather than taping only the outer insulation.
Reroute wiring away from the exhaust, starter cable, ignition coils, and moving parts.
Repair a power or ground circuit that drops out under vibration.
Seal or replace a connector affected by moisture.
Repair a loose or damaged reluctor wheel.
Replace the crankshaft position sensor when the signal disappears at the sensor while its power, ground, wiring, target, and air gap remain correct.

For an intermittent P0339 crankshaft position sensor “A” circuit fault, a normal cold resistance reading is not enough to clear the sensor. The component may fail only when hot or under vibration.

Which Repair Should You Try First?

Do not choose repairs by price or convenience. Use the code behavior to narrow the starting point.

Vehicle behavior	Best first action
Engine cranks but scan data shows 0 RPM	Test CKP power, ground, signal, and connector
Code appeared after sensor replacement	Verify the part number, seating, air gap, connector pins, and relearn requirement
P0336 appeared after timing work	Recheck mechanical timing and CKP/CMP correlation
Code appears mainly during cold cranking	Test battery condition, starter speed, voltage drop, and VR output
Engine stalls hot and restarts after cooling	Monitor CKP signal, power, and ground as temperature rises
P0339 appears over bumps	Inspect terminal tension and perform a harness movement test
P0337 returns immediately	Look for a short to ground or missing sensor supply
P0338 returns immediately	Look for a short to voltage, open signal wire, or missing ground
CKP waveform is clean but P0336 remains	Inspect the reluctor and compare CKP/CMP timing
New sensor did not fix P0335	Return to the wiring, target wheel, cranking speed, and circuit tests

After Completing the Repair

After repairing a P0335, P0336, P0337, P0338, or P0339 fault:

Reconnect and secure the harness.
Confirm the sensor is fully seated.
Clear stored and pending codes.
Start the engine and verify cranking and running RPM.
Check Cam/Crank Sync when available.
Road-test under the original freeze-frame conditions.
Rescan for pending codes.
Perform a crankshaft position variation relearn when required.

Clearing the P0335 fault code is not the same as completing a relearn.

On applicable vehicles, skipping the crankshaft position variation relearn may set P0315 or cause the ECM to interpret normal crankshaft variation as a misfire, potentially contributing to false P0300 codes under load.

Frequently Asked Questions

What Does the P0335 Code Mean?

The P0335 code means that the ECM has detected a malfunction in the crankshaft position sensor “A” circuit or cannot recognize a valid CKP signal.

The code does not prove that the sensor itself has failed.

What Is the Most Common Fix for P0335?

There is no universal P0335 fix. The correct repair depends on the test result.

If power and ground are correct, the target is moving, the air gap is correct, and the sensor produces no output, replacement may be justified. If the sensor produces a signal but it does not reach the ECM, repair the wiring instead.

Where Is the P0335 Crankshaft Position Sensor Located?

The P0335 crankshaft position sensor location varies by engine. It may be near the crankshaft pulley, timing cover, engine block, flywheel, flexplate, or transmission bellhousing.

Use service information to confirm the correct sensor “A” location.

Can a Weak Battery Cause a P0335 Code?

Yes, a weak battery or dragging starter can contribute to a P0335 code by reducing cranking speed and system voltage.

This is especially important with a variable-reluctance CKP sensor because its signal amplitude normally decreases at lower rotational speeds.

What Is the Difference Between P0335 and P0336?

P0335 generally means that no valid CKP signal is recognized. P0336 means a signal is present, but its pattern, timing, frequency, or amplitude is outside the expected range.

What Is the Difference Between P0335 and P0339?

P0335 identifies a general CKP “A” circuit malfunction. P0339 identifies an intermittent CKP signal that drops out or becomes unstable under certain conditions.

What Is the Difference Between P0337 and P0338?

P0337 means the crankshaft position sensor “A” circuit input is lower than expected, while P0338 means the circuit input is higher than expected.

For P0337, check for a signal wire shorted to ground, poor sensor power, excessive ground resistance, low cranking speed, excessive sensor clearance, or weak variable-reluctance sensor output.

For P0338, check for a signal wire shorted to voltage, an open signal circuit, missing sensor ground, or a Hall-effect sensor that cannot switch the signal low.

The exact voltage limits depend on the vehicle and sensor design. Use the correct wiring diagram and manufacturer specifications before repairing the circuit or replacing the crankshaft position sensor.

Can a Bad Timing Chain Cause P0336?

Yes. A stretched, jumped, or incorrectly installed timing chain can shift the relationship between the crankshaft and camshaft signals and produce P0336 or a related correlation code.

Will Replacing the Crankshaft Sensor Fix P0335?

Only if testing confirms that the sensor is defective. Replacing it will not repair damaged wiring, poor power or ground, low cranking speed, incorrect clearance, or a damaged reluctor wheel.

Can You Drive with P0339?

Driving with P0339 is not recommended because an intermittent CKP signal may cause sudden stalling, a no-start condition, or loss of engine power.

Final Thoughts

The fastest way to repair P0335–P0339 is to use each code’s electrical description to choose the first test:

Start P0335 with cranking RPM and basic circuit checks.
Start P0336 with cranking speed, sensor clearance, reluctor condition, and waveform quality.
Start P0337 by checking for low voltage, a short to ground, or weak VR output.
Start P0338 by checking for a short to voltage, an open signal wire, or missing ground.
Start P0339 by reproducing the heat, vibration, or harness conditions that interrupt the signal.

Replace the crankshaft position sensor only when the test results support it. If the sensor circuit is correct, continue to the reluctor wheel, cranking system, CKP/CMP relationship, and mechanical timing.

This approach turns a crankshaft sensor fault code into a clear repair direction instead of another parts-swapping decision.