P0389 OBD-II Trouble Code: Crankshaft Position Sensor B Circuit Intermittent

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0389 code

P0389 is a diagnostic trouble code (DTC) for "Crankshaft Position Sensor B Circuit Intermittent". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0389 DIAGNOSTIC Get a fair and transparent estimate upfront

P0389 code definition

The powertrain control module (PCM) or another related control module has detected a fluctuation in voltage from the crankshaft position sensor (CPS) B circuit that exceeds the maximum allowable variation from manufacturer’s specs.

What the P0389 code means

The manufacturer’s specs allow a 10 percent variation from predetermined reference voltage on the CPS. Variations of more than 10 percent will cause a trouble code to be stored in the powertrain control module (PCM), illuminating the malfunction indicator lamp (MIL). Some vehicles require as many as three failure cycles to illuminate the MIL; however, a “pending code” will be stored without the MIL being illuminated.

What causes the P0389 code?

  • Damaged CPS
  • Damaged sensor connector or wiring
  • Broken crankshaft reluctor ring or missing teeth
  • Broken timing belt wound around cam and crank timing gears can often damage CPS components and wiring
  • Open or shorted power or ground circuits

What are the symptoms of the P0389 code?

How does a mechanic diagnose the P0389 code?

The CPS is a Hall-effect electromagnetic sensor. Some designs use a reluctor ring or teeth attached to the crankshaft, interrupting the field of the electromagnetic sensor and creating a square waveform pattern. These pulses enable the PCM to read the crankshaft position precisely; the PCM uses this information to detect misfires. Engine control systems that use this type of CPS may start and run even with a failure, but performance and fuel economy will be poor. Other designs use the CPS to govern spark timing and ignition control. IN these cases, the CPS failure will usually lead to a no-start condition, stored trouble code and illuminated MIL on the first failure. A good starting point for a successful diagnosis is to check for an engine RPM signal while cranking the engine. This can be done by observing the vehicle’s dashboard tachometer or by using a scanner, depending on the CPS system design.

  • If no RPM signal can be detected, visually inspect the crankshaft gear, CPS and sensor connector for damage. Repair/replace as needed.
  • If no damage is evident, test the CPS system for a reference voltage signal. Voltage is usually five volts – check manufacturer’s specs.
  • Use an oscilloscope to test the CPS signal wire for a square 5-volt waveform pattern on every engine revolution.
  • If no pattern is detected, test the resistance of the disconnected CPS sensor. Compare resistance to manufacturer’s specs.
  • If the CPS sensor is good, test the system circuitry for proper voltage/resistance. Repair any open or shorted wiring as needed.

Common mistakes when diagnosing the P0389 code

Timing components should be inspected closely when replacing a broken or worn timing belt, if an engine fails to start afterwards due to a damaged gear, sensor, connector, reluctor ring or wiring. Loose or corroded electrical wiring or connectors are also a possibility.

How serious is the P0389 code?

A P0389 code can result in a vehicle that performs very poorly or won’t start at all.

What repairs can fix the P0389 code?

Additional comments for consideration regarding the P0389 code

On vehicles equipped with distributors, the distributor’s Hall-effect sensor, camshaft position sensor and crank position sensor work together to help govern ignition timing and fuel delivery strategies. Engines with multiple camshafts will have multiple CPS sensors. In the event of an intermittent condition, use the oscilloscope to analyze waveforms from the distributor and crank sensors as well, while looking for spikes or glitches in the waveform. These sensors have been known to become contaminated with oil, antifreeze or power steering fluid leaks. Look closely for worn or deteriorated wiring or connectors.

On older vehicles with distributors, test the distributor for slop, end-play and side-to-side wobble along with tests of the sensors.

Need help with a P0389 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

OBD-II
trouble codes
P0389

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0389 code.

SCHEDULE P0389 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


More related articles

P2054 OBD-II Trouble Code: Reductant Injector Circuit Low Bank 1 Unit 2
P2054 P2054 trouble code definition Reductant Injector Circuit Low Bank 1 Unit 2 What the P2054 code means This code indicates a problem with the circuit that controls the reductant injector. The terms “circuit low” refers to a lower than...
P0701 OBD-II Trouble Code: Transmission Control System Range/Performance
P0701 means a malfunction in the automatic control system has been detected. Issues may include transmission failure, overheating and engine stalling.
P0789 OBD-II Trouble Code: Shift/Timing Solenoid Intermittent
P0789 code means there is an issue with the gear ratio within the vehicle often due too a faulty shift solenoid or transmission blockages.

Related questions

wont go faster 35mph
If the Check Engine Light is on this would be helpful as the codes that would be triggered by this would generate useful information relating to the problem. Without the benefit of hooking the car up to a scanner and...
P0016 (crankshaft and camshaft correlation bank 1 sensor A)
Hello. Trouble code P0016 (https://www.yourmechanic.com/article/p0016-obd-ii-trouble-code-camshaft-position-a-camshaft-position-correlation-bank-1-by-jay-safford) is set when the computer detects that there is an issue with the timing between the engine's camshaft and crankshaft signals. The camshaft and crankshafts are connected by a belt or chain, and are precisely...
I have a 2012 cc with a p0016 code no start. chain is tight and all turns freely when turned by hand
Code P0016 (https://www.yourmechanic.com/article/p0016-obd-ii-trouble-code-camshaft-position-a-camshaft-position-correlation-bank-1-by-jay-safford) broadly means that the PCM has detected that the Crankshaft and Camshaft are out of sync. If they are out of sync beyond a specific, threshold number of degrees, the car simply won't start. The cause of...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com