How to handle random car error codes and weird driving feelings
Car error codes often pop up alongside intermittent physical symptoms like strange noises or jolting, forcing drivers to guess whether a part just needs cleaning or if an old repair failed. This ambiguity leaves people stuck trying to diagnose issues themselves by checking fluids and sensors, or debating whether to return to a mechanic for unresolved problems.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 11.8× more often in r/MechanicAdvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1cleaning components like sensorsDid this help you?
- 2taking the car back to the repair shopDid this help you?
- 3turning the vehicle off and on to see if the light goes awayDid this help you?
- 4scanning the engine computer for stored fault codesDid this help you?
- 5Deleting the trouble codesDid this help you?
- 6Replacing the car batteryDid this help you?
- 7Checking connectors for moistureDid this help you?
- 8Avoiding direct water spray at gaps in the vehicle bodyDid this help you?
- 9Using an OBDII code scanner to check for diagnostic trouble codesDid this help you?
- 10Visiting an auto parts store for a free code scanDid this help you?
- 11Taking the vehicle to a trusted mechanic or independent shop for professional diagnosisDid this help you?
- 12Replacing oxygen sensors, checking for a torn boot, or inspecting the mass airflow sensorDid this help you?
- 13Scanning codes with diagnostic tools like BimmerLinkDid this help you?
- 14Having a mechanic test wiring harnesses and replace componentsDid this help you?
- 15taking the car to a mechanic shopDid this help you?
- 16getting codes read at an auto parts store like AutoZone, NAPA, or O'ReillyDid this help you?
- 17scanning codes using an OBD2 connectorDid this help you?
- 18Getting the check engine light scanned at an auto parts storeDid this help you?
- 19Scanning codes at an auto parts storeDid this help you?
- 20Searching online forums for troubleshooting adviceDid this help you?
- 21Planning to take the vehicle to a professional mechanicDid this help you?
- 22leaving the car parkedDid this help you?
- 23having the vehicle towedDid this help you?
- 24reading online forums to interpret error codesDid this help you?
- 25replacing parts like speed sensorsDid this help you?
- 26clearing DTC codes repeatedlyDid this help you?
- 27testing resistance and continuity with a multimeterDid this help you?
- 28checking live view data via an OBD2 scannerDid this help you?
- 29Taking the battery out and putting it back inDid this help you?
- 30Disconnecting the battery for 15-20 minutes for a deeper resetDid this help you?
- 31Towing the vehicle to the dealership instead of drivingDid this help you?
- 32Going to a mechanic for interpretation and repairDid this help you?
- 33Driving around for a few days or hours to let emissions monitors resetDid this help you?
- 34Getting the car scanned at an auto parts storeDid this help you?
- 35Checking or tightening the gas capDid this help you?
- 36Clearing the code to see if it returns before buying replacement partsDid this help you?
- 37Waiting to hear back from the techniciansDid this help you?
- 38Considering clearing the code with a personal readerDid this help you?
- 39Making the shop re-diagnose and fix the issue properlyDid this help you?
- 40Waiting for backordered parts at the dealershipDid this help you?
- 41Consulting mechanics and seeking advice on forumsDid this help you?
- 42Asking online communities for troubleshooting adviceDid this help you?
- 43Replacing all parts related to the codesDid this help you?
- 44Asking AI for preliminary diagnosticsDid this help you?
- 45Taking the car to a repair shop for professional diagnosisDid this help you?
- 46Asking a mechanic online for adviceDid this help you?
- 47Requesting a pre-purchase scan or professional inspectionDid this help you?
- 48Asking the seller to fix the issue before purchasingDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“My check engine came on about a week ago so. I went to AutoZone today to get it checked out before going to a mechanic. Is the secondary DTC error codes something that happened in the past and it was stored in the memory or something that’s why it came up?”source ↗
“I’m just confused because everything says passed and then these codes show up.”source ↗
“As for the emissions, is that something I have to reset or drive a certain amount for for that to be emissions ready? Am I fine and will my check engine light eventually go away or should I reset that manually?”source ↗
“The girl at AutoZone that helped out said she doesn’t know what it means but that I have to go get it fixed at the mechanic? Sorry for all of the questions, I just have no idea.”source ↗
“Got these codes, the MAD sensor looks good so I’m gonna try cleaning it first.”source ↗
“I got a bunch of brake codes, I checked the brake fluid and it was good.”source ↗
“The brake assembly in the back did fall apart last June. I got it repaired at a shop for 1700 usd. I’m going to take it back to the shop for the brake codes.”source ↗
“I noticed my EPC light come on the other day before class. I parked and left my car off and when I came back it was off. The light came back on while on the highway to work this morning and I felt like it sounded louder than normal and maybe a bit of a jotting around feeling.”source ↗
“Today after a car wash, code P0607 appeared but the car starts and runs fine.”source ↗
“Had a car wash in May. 24 hours later, car struggled to start, exhaust emitted white fumes and threw P0607 and P0138 codes.”source ↗
“I've got a 2004 ES330, only code is P0430 (Bank 2 efficiency) and I already did the cats and gaskets. Cleared the code, drove it and 2 days later the code popped again. Need the emissions done by the 15th, is my only option the sensors, or is there anything else I should try first?”source ↗
“Today, 5 days later, after the car had already been running for a few minutes, it did a noticeable shake/shiver at idle like the revs dipped and recovered.”source ↗
“A bit later it started idling rough again, not as bad as the first time, and then threw the “Drivetrain – You can continue driving” warning again.”source ↗
“started displaying the check engine and AWD light simultaneously when i turned it on this morning. tried re-screwing the fuel cap but that doesn’t seem to have worked. should i take it into the shop or just wait it out? my car has literally no other symptoms, its driving perfect.”source ↗
“My check engine light was ON this morning after driving for 5 miles and I got it checked with Autozone and they said it is a thermostat failure.”source ↗
“How serious is this and how soon should it be fixed and can this be a DIY?”source ↗
“I got a p0796 and a p0741 code read on my 2006 Toyota Sienna that I'm pretty sure transmission went or is going out on from what I was reading it's torque converter and electrical problem in the transmission.”source ↗
“If someone could help me understand how to fix it or give me a price range on taking it to a mechanic'd appreciate at it.”source ↗
“When the incident happened, about 4 to 5 months ago, it leaked out 2qts of transmission fluid and oil in about 10 minutes.”source ↗
“Replaced them all ... tried to reset the code. Nothing. Tried a few other times, nothing. Tried to Clear DTC, then do the key off/on thing 20 times, nothing.”source ↗
“Pulled codes again, and now I have 3. P0700(70-2) A/T System Malfunction / P0740(40-1) Failure of Torque Converter Clutch System - and the 15-01.”source ↗
“I'm at a loss. I think if I can get the 15-1 fixed, I can start diagnosing the others if they show up.”source ↗
“I got a brake system error, cruise control error, and lane departure error. I drove it to O’Reilly and no codes were coming up on their reader.”source ↗
“The car decelerates gradually on its own randomly when driving.”source ↗
“Please help. I can’t afford a huge car maintenance bill and car issues make me sick to my stomach.”source ↗
“Hello, I just got my first car, a 2011 Nissan Altima 2.5S Special Edition with a CVT engine, and yesterday, when I was driving, my check engine light came on. I was concerned, and I went to O'Reilly's to get it scanned.”source ↗
“What I don’t really understand is the last 3 codes.”source ↗
“Restraint system: Contact BMW. Fault in airbag, belt tensioner or belt-force limiter. Continue wearing safety belt. Consult nearest service center.”source ↗
“Looks like dudes lying to you and it needs some safety equipment of some sort”source ↗
“If it was easy to fix, he would have fixed it himself.”source ↗
“About a day after getting the AC compressor to my wife's Mini Cooper replaced a CEL popped up.”source ↗
“Took it to O'Reilys and it was throwing a P0171 code.”source ↗
“I'm going to take it to a mechanic because I clearly don't understand what I'm dealing with”source ↗
“1. Is this an urgent issue or is this something that I could preferably put off until my next paycheck?”source ↗
“3. Could this at all be related to getting the compressor replaced? I'm only asking because of the timing.”source ↗
“Started the car, and they all came on. None were on earlier in the day when I used the car to go to work. Car starts runs and drives as usual with them on.”source ↗
“I started using my pedal parking brake over the last few weeks and I read that could cause it, but I’ve made sure to fully disengage it and the lights aren’t going away”source ↗
“I took it the dealership for a diagnosis. The code is P0025. They said they swapped it and if check engine comes back then bring it back. The next day the check engine came back on.”source ↗
“Left my truck there at the dealership for 2 weeks. I went to pick up and right when I turned on my truck the check light is still on.”source ↗
“I’m super stressed out because I already paid $800 total for everything.”source ↗
“My car isn’t driving with full power, rough idling, low coolant no leak, & jolting/jerking I have some codes : P0301 P2651 U041668”source ↗
“if the cost is super high idk what I’ll do My dealer had me waiting for a fuel pump as it was on back order so i never got that fixed.”source ↗
“Should I get both repairs dobe at dealer? Or do they go hand in hand? I honestly would only want to get the free service from them unless I have to get both done at once type of thing”source ↗
Where this came up
People with this problem also raised
- 15Car repair shop broke my car and wants more money
- 13Used car broke down immediately after buying from a dead dealership
- 17Dashboard warning lights stay on but OBD2 scanner shows no errors
- 2Should I tell a mechanic what I think is wrong with my car?
- 2Driving a damaged car when you can't afford the repairs
- 8What does a ticking engine noise and flashing check engine light mean?