REREV

Car advice put simply.

  • Articles
  • Cars
    • Celebrity car collections
    • Car years to avoid
    • OBD2 codes
  • Engines
    • Firing orders
  • Tires
    • Tire and store reviews
  • Glossary
  • Statistics

P1521 code — how to fix error fast

The P1521 code reveals vital aspects of oil viscosity. Navigate its meaning to maintain engine health.

A person holding a psi sensor in a car.
A man in a blue jacket smiling in front of a red wall.
Filip Gromovic July 3, 2023 |

The OBD2 error code P1521 can be pretty bad because you can already assume it has something to do with the powertrain of your car. However, the hard part is getting to the bottom of the P1521 code meaning and getting to see how the code affects your car.

While it’s recommended to visit a trusted mechanic right away, you could use a few starting tips and pieces of advice from qualified automotive experts. So, our team decided to combine the knowledge of different team members into one comprehensive guide on diagnosing code P1512, fixing it, and making sure it never happens again.

Why you can trust REREV’s OBD2 code advice: Our automotive expert researchers with experienced mechanics undertakes a thorough research methodology to deliver precise insights on OBD codes. Find out more about OBD2 codes research process..

What does the P1521 code mean?

The P1521 code indicates an issue with the camshaft position sensor (CMP), which is responsible for sending signals to the engine control module (ECM) about the camshaft’s position. The ECM uses this information to control the fuel injection and ignition timing.

If the camshaft position sensor is malfunctioning, the ECM will not receive the correct information, leading to poor engine performance, decreased fuel efficiency, and increased emissions.

What causes the P1521 code?

There are several potential causes of the P1521 code, and it’s important to get to know all the potential reasons behind the code before you get to the fixing stage. So, here’s an overview of the three most plausible suspects:

Faulty camshaft position sensor

The most common cause of the P1521 code is a faulty camshaft position sensor. Over time, the sensor may become worn out or damaged, leading to incorrect readings. Symptoms of a faulty camshaft position sensor include rough idling, stalling, and difficulty starting the engine.

Wiring issues

Another potential cause of the P1521 code is wiring issues. Damaged or corroded wires can cause electrical interference and prevent the camshaft position sensor from functioning correctly. Symptoms of wiring issues include sporadic engine performance and check engine light illumination.

Failed ECM

In some cases, the P1521 code may be caused by a malfunctioning ECM. This is a less common cause, and symptoms may include engine misfires and difficulty starting the engine.

Which car models does the P1521 code affect the most?

Car models that have a high occurrence of the P1521 code mostly suffer from the location of the camshaft position sensor in the engine. It can be challenging to reach and, therefore, may often cause the code P1512 to trigger on your scanner tool. We’ve done some digging on such cars and here’s a list of the rides that are most commonly affected by the code:

  • Jeep Grand Cherokee: This SUV has had numerous reports of P1521 issues, with symptoms including difficulty shifting gears, stalling, and loss of power.
  • Dodge RAM: The Ram pickup truck has also been known to experience P1521 issues, particularly in older models.
  • Chrysler 300: This luxury sedan has had reports of transmission range sensor problems, resulting in harsh shifting, stalling, and other issues.

How to diagnose the P1521 code

Diagnosing the P1521 code requires doing several different tests to determine the real reason behind the code’s activation. Depending on what seems to be the cause of the code in your car, here’s what you can do to diagnose the problem:

Scan the vehicle’s diagnostic system

The first step in diagnosing the P1521 code is to scan the vehicle’s diagnostic system using an OBD-II scanner. The scanner will read the code and provide additional information about the issue.

Inspect the camshaft position sensor

Next, the mechanic should inspect the camshaft position sensor for any visible signs of damage or wear. They should also check the wiring for any signs of damage or corrosion.

Perform a voltage test

The mechanic should perform a voltage test to ensure that the camshaft position sensor is receiving and transmitting the correct signals.

How to fix the P1521 code

Fixing the P1521 code depends on the root cause of the issue. Once you’ve successfully diagnosed the culprit, you can use one of the following solutions depending on what went wrong with your car:

Replacing the camshaft position sensor

If the issue is with the camshaft position sensor, the mechanic should replace the sensor with a new one. The cost of replacing the sensor can range from $100 to $200.

Repairing wiring issues

If the issue is with the wiring, the mechanic should repair or replace the damaged wires. The cost of repairing wiring issues can range from $50 to $200.

Replacing the ECM

If the issue is with the ECM, the mechanic should replace the module with a new one. The cost of replacing the ECM can range from $500 to $1000.

It is essential to fix the P1521 code as soon as possible to prevent any further damage to your vehicle. If you are unsure about how to fix the code, seek professional help.

How to prevent the P1521 code

Preventing the P1521 code involves proper maintenance of your vehicle’s engine. Some preventative measures include:

  • Regularly changing the engine oil
  • Replacing the camshaft position sensor as recommended by the manufacturer
  • Avoiding harsh driving conditions, such as extreme temperatures or heavy loads

Proper maintenance of your vehicle’s engine can go a long way in preventing the P1521 code. If you suspect an issue with your vehicle’s engine, it is always best to seek professional help to diagnose and fix the issue.

Our take

Well, there you have it – we’ve shared all of our insights on the code P1521 with you so you can use the information from this guide to benefit your car. There’s nothing worse than experiencing engine issues and poor acceleration because of the code, so we are hoping this guide will suffice in helping you out with it.

What are the symptoms of a P1521 code?

Symptoms of a P1521 code can include difficulty shifting gears, stalling, or loss of power.

Can I still drive my car if it has a P1521 code?

It is not recommended to continue driving your vehicle if it is experiencing symptoms related to the P1521 code. Ignoring this issue can lead to further damage to your vehicle’s transmission and can result in costly repairs down the road.

How is a P1521 code diagnosed?

A certified mechanic will use a scan tool to retrieve the fault codes stored in your vehicle’s computer system. They will then perform a visual inspection of the transmission range sensor and its wiring and connections to verify that there are no visible issues.

Previous post: P2238 code
Next post: P0672 code
  • Filip Gromovic
    Filip Gromovic

    Filip is a lifelong car enthusiast with over 3 years of experience writing about cars and had worked as a mechanic apprentice for over 5 years, gaining hands-on expertise in automotive mechanics. At REREV, he combines his passion for cars with his comprehensive knowledge to provide readers with a unique blend of technical insight and engaging storytelling that sets the bar high for automotive content.

    Recent Posts
    P0571 code — how to fix error fast
    P2074 code — how to fix error fast
    P0301 code — how to fix error fast
REREV logo

Website

  • About
  • Editorial Guidelines
  • Contact
  • Terms
  • Privacy

Car Insights

  • Years to avoid
  • Collections
  • Statistics
  • Glossary

© 2025 REREV. All rights reserved.