OBD codes 300, 502, 503, 151

Welcome to 2CarPros.

The P0300 is a random misfire and could be caused by several different things. Yes, the misfire can be related to the heated O2 sensor issue (P0151). However, not to the speed sensor issues.

Now, the o2 sensor code indicates there is too much oxygen in the exhaust. Most times that is related to an engine vacuum leak which can cause a random misfire. With that in mind, I would first check for engine vacuum leaks. Here is a link that shows how it is done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you find there are no leaks, then check and confirm that the fuel pump pressure is within the manufacturer's specs. Here is a link that shows how that is done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look at the attached pictures, they are diagnostic flow charts related to fuel pressure issues in case you find the pressure is not correct. The last pic provides the manufacturer's specs for pressure.

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Lets start with this and let me know what you find. Honestly, to just replace the coils and sensor may not fix the issue.

Let me know what you find.

Take care,
Joe

Hello,

There are two separate issues going on here Direct Trouble Codes (DTC)(s) P0300 and DTC P0151 are one issue and DTC P)502 and DTC P0503 are another issue. In the diagrams down below I have included factory description and troubleshooting diagnostic flowcharts for each of the four DTC's for you to go through. It is a lot of information, but please go through each one and keep in mind that there are two separate issues here. Please get back to us with what you find out.

Thanks,
Alex
2CarPros

Hello again,

DTC's continued in the diagrams down below.

Thanks,
Alex
2CarPros

Welcome back:

That sounds like a plan. Let me know what you find or if you have other questions.

Joe