Dear Forum Members,I wanted to get an opinion with an ongoing issue. I have a BMW 318i, i had to take it into the garage because the coolant was leaking—apparently a housing part cracked, causing a seal to fold in and fail. The mechanic replaced that part, but after doing so, two warning lights came on. Even though he ran diagnostics and everything looked fine, he couldn’t explain the cause. I had an MOT booked for later that day, and although he said it may not pass, he took it in, and it passed. However, the warning lights are still on. He said he called out an auto electrician, but failed to find the cause, as he said the diagnostic test couldn't find a fault. He said a possibility could be where he's had the battery disconnected for so long, because he's had it about four or five days, something to do with the memory not resetting itself and could possibly go off in a few days or after drivingI.. he hasn't asked for payment yet for the original fault. Do I be consider haggling price and taking the car elsewhere, or tell the garage (politely) no I'm not happy taking car until its fixed.. thank you, Cliffy.
Do I take the car?
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11-04-26 13:33What warning lights are on? I began having both management lights coming on occasionally, and it turned out to be a worn timing chain.
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12-04-26 13:04Get the garage to get advice from BMW!
As @Rolebama says what warning lights?
One easy thing would be to disconnect the battery for, say, 10 mins then reconnect, it may clear the warnings but it's a long shot.
The idea that the memory may clear after a few days running is unlikely to work.
It is possible to mess things up if connecting the battery was not cleanly done, my instinct would be to connect negative first then positive but firmly to prevent intermittent (sparkey) contact as the power goes on. -
15-04-26 01:55
You can clear a check engine light by disconnecting the battery for a while but the PCM will still perform monitor tests.
For example, the catalytic converter will be tested when the engine temperature is at a certain level and the car is being driven at a certain steady speed. The PCM then tests the response time of both the upstream and down stream oxygen sensors.
If everything is OK it will move onto the next test, if not the check engine light will come back on. The car does these monitor tests constantly.
When I was smog testing cars in Vegas the DMV had a handout we gave those who failed the smog test because even though the check engine light was out (they had disconnected the battery to turn it off), the monitors hadn't set and it failed the test.
